Q-Chem 5.1 User’s Manual

C.4 Alphabetical Listing of $rem Variables

EIGSLV_METH

Control the method for solving the ALMO-CIS eigen-equation


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Explicitly build the Hamiltonian then diagonalize (full-spectrum).

1

Use the Davidson method (currently only available for restricted cases).


RECOMMENDATION:

None


LOCAL_CIS

Invoke ALMO-CIS/ALMO-CIS+CT.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Regular CIS

1

ALMO-CIS/ALMO-CIS+CT without RI(slow)

2

ALMO-CIS/ALMO-CIS+CT with RI


RECOMMENDATION:

2 if ALMO-CIS is desired.


NN_THRESH

The distance cutoff for neighboring fragments (between which CT is enabled).


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not include interfragment transitions (ALMO-CIS).

$n$

Include interfragment excitations between pairs of fragments the distances between whom

 

are smaller than $n$ Bohr (ALMO-CIS+CT).


RECOMMENDATION:

None


FDIFF_STEPSIZE

Displacement used for calculating derivatives by finite difference.


TYPE:

INTEGER


DEFAULT:

1

Corresponding to $1.88973\times 10^{-5}$ a.u.


OPTIONS:

$n$

Use a step size of $n$ times the default value.


RECOMMENDATION:

Use the default unless problems arise.


RESPONSE_POLAR

Control the use of analytic or numerical polarizabilities.


TYPE:

INTEGER


DEFAULT:

0 or $-$1

= 0 for HF or DFT, $-$1 for all other methods


OPTIONS:

0

Perform an analytic polarizability calculation.

$-$1

Perform a numeric polarizability calculation even when analytic 2nd derivatives are available.


RECOMMENDATION:

None


ADC_CVS

Activates the use of the CVS approximation for the calculation of CVS-ADC core-excited states.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Activates the CVS approximation.

FALSE

Do not compute core-excited states using the CVS approximation.


RECOMMENDATION:

Set to TRUE, if to obtain core-excited states for the simulation of X-ray absorption spectra. In the case of TRUE, the $rem variable CC_REST_OCC has to be defined as well.


ADC_C_C

Set the spin-opposite scaling parameter $c_ c$ for the ADC(2) calculation. The parameter value is obtained by multiplying the given integer by $10^{-3}$.


TYPE:

INTEGER


DEFAULT:

1170

Optimized value $c_ c=1.17$ for ADC(2)-s or

1000

$c_ c=1.0$ for ADC(2)-x


OPTIONS:

$n$

Corresponding to $n \cdot 10^{-3}$


RECOMMENDATION:

Use the default.


ADC_C_T

Set the spin-opposite scaling parameter $c_ T$ for an SOS-ADC(2) calculation. The parameter value is obtained by multiplying the given integer by $10^{-3}$.


TYPE:

INTEGER


DEFAULT:

1300

Optimized value $c_ T = 1.3$.


OPTIONS:

$n$

Corresponding to $n \cdot 10^{-3}$


RECOMMENDATION:

Use the default.


ADC_C_X

Set the spin-opposite scaling parameter $c_ x$ for the ADC(2)-x calculation. The parameter value is obtained by multiplying the given integer by $10^{-3}$.


TYPE:

INTEGER


DEFAULT:

1300

Optimized value $c_ x = 0.9$ for ADC(2)-x.


OPTIONS:

$n$

Corresponding to $n \cdot 10^{-3}$


RECOMMENDATION:

Use the default.


ADC_DAVIDSON_CONV

Controls the convergence criterion of the Davidson procedure.


TYPE:

INTEGER


DEFAULT:

$6$

Corresponding to $10^{-6}$


OPTIONS:

$n \leq 12$

Corresponding to $10^{-n}$.


RECOMMENDATION:

Use the default unless higher accuracy is required or convergence problems are encountered.


ADC_DAVIDSON_MAXITER

Controls the maximum number of iterations of the Davidson procedure.


TYPE:

INTEGER


DEFAULT:

60


OPTIONS:

$n$

Number of iterations


RECOMMENDATION:

Use the default unless convergence problems are encountered.


ADC_DAVIDSON_MAXSUBSPACE

Controls the maximum subspace size for the Davidson procedure.


TYPE:

INTEGER


DEFAULT:

$5 \times $ the number of excited states to be calculated.


OPTIONS:

$n$

User-defined integer.


RECOMMENDATION:

Should be at least $2-4 \times $ the number of excited states to calculate. The larger the value the more disk space is required.


ADC_DAVIDSON_THRESH

Controls the threshold for the norm of expansion vectors to be added during the Davidson procedure.


TYPE:

INTEGER


DEFAULT:

Twice the value of ADC_DAVIDSON_CONV, but at maximum $10^{-14}$.


OPTIONS:

$n \leq 14 $

Corresponding to $10^{-n}$


RECOMMENDATION:

Use the default unless convergence problems are encountered. The threshold value $10^{-n}$ should always be smaller than the convergence criterion ADC_DAVIDSON_CONV.


ADC_DIIS_ECONV

Controls the convergence criterion for the excited state energy during DIIS.


TYPE:

INTEGER


DEFAULT:

6

Corresponding to $10^{-6}$


OPTIONS:

$n$

Corresponding to $10^{-n}$


RECOMMENDATION:

None


ADC_DIIS_MAXITER

Controls the maximum number of DIIS iterations.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

User-defined integer.


RECOMMENDATION:

Increase in case of slow convergence.


ADC_DIIS_RCONV

Convergence criterion for the residual vector norm of the excited state during DIIS.


TYPE:

INTEGER


DEFAULT:

6

Corresponding to $10^{-6}$


OPTIONS:

$n$

Corresponding to $10^{-n}$


RECOMMENDATION:

None


ADC_DIIS_SIZE

Controls the size of the DIIS subspace.


TYPE:

INTEGER


DEFAULT:

7


OPTIONS:

$n$

User-defined integer


RECOMMENDATION:

None


ADC_DIIS_START

Controls the iteration step at which DIIS is turned on.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$n$

User-defined integer.


RECOMMENDATION:

Set to a large number to switch off DIIS steps.


ADC_DO_DIIS

Activates the use of the DIIS algorithm for the calculation of ADC(2) excited states.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Use DIIS algorithm.

FALSE

Do diagonalization using Davidson algorithm.


RECOMMENDATION:

None.


ADC_NGUESS_DOUBLES

Controls the number of excited state guess vectors which are double excitations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined integer.


RECOMMENDATION:

ADC_NGUESS_SINGLES

Controls the number of excited state guess vectors which are single excitations. If the number of requested excited states exceeds the total number of guess vectors (singles and doubles), this parameter is automatically adjusted, so that the number of guess vectors matches the number of requested excited states.


TYPE:

INTEGER


DEFAULT:

Equals to the number of excited states requested.


OPTIONS:

$n$

User-defined integer.


RECOMMENDATION:

ADC_PRINT

Controls the amount of printing during an ADC calculation.


TYPE:

INTEGER


DEFAULT:

1

Basic status information and results are printed.


OPTIONS:

0

Quiet: almost only results are printed.

1

Normal: basic status information and results are printed.

2

Debug: more status information, extended information on timings.

...


RECOMMENDATION:

Use the default.


ADC_PROP_ES2ES

Controls the calculation of transition properties between excited states (currently only transition dipole moments and oscillator strengths), as well as the computation of two-photon absorption cross-sections of excited states using the sum-over-states expression.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculate state-to-state transition properties.

FALSE

Do not compute transition properties between excited states.


RECOMMENDATION:

Set to TRUE, if state-to-state properties or sum-over-states two-photon absorption cross-sections are required.


ADC_PROP_ES

Controls the calculation of excited state properties (currently only dipole moments).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculate excited state properties.

FALSE

Do not compute state properties.


RECOMMENDATION:

Set to TRUE, if properties are required.


ADC_PROP_TPA

Controls the calculation of two-photon absorption cross-sections of excited states using matrix inversion techniques.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculate two-photon absorption cross-sections.

FALSE

Do not compute two-photon absorption cross-sections.


RECOMMENDATION:

Set to TRUE, if to obtain two-photon absorption cross-sections.


ADD_CHARGED_CAGE

Add a point charge cage of a given radius and total charge.


TYPE:

INTEGER


DEFAULT:

0

No cage.


OPTIONS:

0

No cage.

1

Dodecahedral cage.

2

Spherical cage.


RECOMMENDATION:

Spherical cage is expected to yield more accurate results, especially for small radii.


AFSSH

Adds decoherence approximation to surface hopping calculation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Traditional surface hopping, no decoherence.

1

Use augmented fewest-switches surface hopping (AFSSH).


RECOMMENDATION:

AFSSH will increase the cost of the calculation, but may improve accuracy for some systems. See Refs.  Subotnik:2011a,Subotnik:2011b,Landry:2012 for more detail.


AIFDEM_CTSTATES

Include charge-transfer-like cation/anion pair states in the AIFDEM basis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Include CT states.

FALSE

Do not include CT states.


RECOMMENDATION:

None


AIFDEM_EMBED_RANGE

Specifies the size of the QM region for charge embedding


TYPE:

INTEGER


DEFAULT:

FULL_QM


OPTIONS:

FULL_QM

No charge embedding.

0

Treat only excited fragments with QM.

$n$

Range (Å) from excited fragments within which to treat other fragments with QM.


RECOMMENDATION:

Minimal, 0 Å, threshold maintains accuracy while significantly reducing computational time.


AIFDEM_NTOTHRESH

Controls the number of NTOs that are retained in the exciton-site basis states.


TYPE:

INTEGER


DEFAULT:

99


OPTIONS:

$n$

Threshold percentage of the norm of fragment NTO amplitudes.


RECOMMENDATION:

A threshold of $85 \% $ gives a good trade-off of computational time and accuracy for organic molecules.


AIFDEM

Perform an AIFDEM calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform an AIFDEM calculation.

TRUE

Perform an AIFDEM calculation.


RECOMMENDATION:

False


AIMD_FICT_MASS

Specifies the value of the fictitious electronic mass $\mu $, in atomic units, where $\mu $ has dimensions of (energy)$\times $(time)$^{2}$.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

User-specified


RECOMMENDATION:

Values in the range of 50–200 a.u. have been employed in test calculations; consult Ref. Herbert:2004 for examples and discussion.


AIMD_INIT_VELOC

Specifies the method for selecting initial nuclear velocities.


TYPE:

STRING


DEFAULT:

None


OPTIONS:

THERMAL

Random sampling of nuclear velocities from a Maxwell-Boltzmann

 

distribution. The user must specify the temperature in Kelvin via

 

the $rem variable AIMD_TEMP.

ZPE

Choose velocities in order to put zero-point vibrational energy into

 

each normal mode, with random signs. This option requires that a

 

frequency job to be run beforehand.

QUASICLASSICAL

Puts vibrational energy into each normal mode. In contrast to the

 

ZPE option, here the vibrational energies are sampled from a

 

Boltzmann distribution at the desired simulation temperature. This

 

also triggers several other options, as described below.


RECOMMENDATION:

This variable need only be specified in the event that velocities are not specified explicitly in a $velocity section.


AIMD_LANGEVIN_TIMESCALE

Sets the timescale (strength) of the Langevin thermostat


TYPE:

INTEGER


DEFAULT:

none


OPTIONS:

$n$

Thermostat timescale,asn $n$ fs


RECOMMENDATION:

Smaller values (roughly 100) equate to tighter thermostats but may inhibit rapid sampling. Larger values ($\geq 1000$) allow for more rapid sampling but may take longer to reach thermal equilibrium.


AIMD_METHOD

Selects an ab initio molecular dynamics algorithm.


TYPE:

STRING


DEFAULT:

BOMD


OPTIONS:

BOMD

Born-Oppenheimer molecular dynamics.

CURVY

Curvy-steps Extended Lagrangian molecular dynamics.


RECOMMENDATION:

BOMD yields exact classical molecular dynamics, provided that the energy is tolerably conserved. ELMD is an approximation to exact classical dynamics whose validity should be tested for the properties of interest.


AIMD_MOMENTS

Requests that multipole moments be output at each time step.


TYPE:

INTEGER


DEFAULT:

0

Do not output multipole moments.


OPTIONS:

$n$

Output the first $n$ multipole moments.


RECOMMENDATION:

None


AIMD_NUCL_DACF_POINTS

Number of time points to use in the dipole auto-correlation function for an AIMD trajectory


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not compute dipole auto-correlation function.

$1\leq n \leq \mbox{{\small AIMD\_ STEPS}}$

Compute dipole auto-correlation function for last $n$

 

timesteps of the trajectory.


RECOMMENDATION:

If the DACF is desired, set equal to AIMD_STEPS.


AIMD_NUCL_SAMPLE_RATE

The rate at which sampling is performed for the velocity and/or dipole auto-correlation function(s). Specified as a multiple of steps; i.e., sampling every step is 1.


TYPE:

INTEGER


DEFAULT:

None.


OPTIONS:

$1\leq n \leq \mbox{{\small AIMD\_ STEPS}}$

Update the velocity/dipole auto-correlation function

 

every $n$ steps.


RECOMMENDATION:

Since the velocity and dipole moment are routinely calculated for ab initio methods, this variable should almost always be set to 1 when the VACF/DACF are desired.


AIMD_NUCL_VACF_POINTS

Number of time points to use in the velocity auto-correlation function for an AIMD trajectory


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not compute velocity auto-correlation function.

$1\leq n \leq \mbox{{\small AIMD\_ STEPS}}$

Compute velocity auto-correlation function for last $n$

 

time steps of the trajectory.


RECOMMENDATION:

If the VACF is desired, set equal to AIMD_STEPS.


AIMD_QCT_INITPOS

Chooses the initial geometry in a QCT-MD simulation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$0$

Use the equilibrium geometry.

$n$

Picks a random geometry according to the harmonic vibrational wave function.

$-n$

Generates $n$ random geometries sampled from

 

the harmonic vibrational wave function.


RECOMMENDATION:

None.


AIMD_QCT_WHICH_TRAJECTORY

Picks a set of vibrational quantum numbers from a random distribution.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$n$

Picks the $n$th set of random initial velocities.

$-n$

Uses an average over $n$ random initial velocities.


RECOMMENDATION:

Pick a positive number if you want the initial velocities to correspond to a particular set of vibrational occupation numbers and choose a different number for each of your trajectories. If initial velocities are desired that corresponds to an average over $n$ trajectories, pick a negative number.


AIMD_SHORT_TIME_STEP

Specifies a shorter electronic time step for FSSH calculations.


TYPE:

INTEGER


DEFAULT:

TIME_STEP


OPTIONS:

$n$

Specify an electronic time step duration of $n$/AIMD_TIME_STEP_CONVERSION

 

a.u. If $n$ is less than the nuclear time step variable TIME_STEP, the

 

electronic wave function will be integrated multiple times per nuclear time step,

 

using a linear interpolation of nuclear quantities such as the energy gradient and

 

derivative coupling. Note that $n$ must divide TIME_STEP evenly.


RECOMMENDATION:

Make AIMD_SHORT_TIME_STEP as large as possible while keeping the trace of the density matrix close to unity during long simulations. Note that while specifying an appropriate duration for the electronic time step is essential for maintaining accurate wave function time evolution, the electronic-only time steps employ linear interpolation to estimate important quantities. Consequently, a short electronic time step is not a substitute for a reasonable nuclear time step.


AIMD_STEPS

Specifies the requested number of molecular dynamics steps.


TYPE:

INTEGER


DEFAULT:

None.


OPTIONS:

User-specified.


RECOMMENDATION:

None.


AIMD_TEMP

Specifies a temperature (in Kelvin) for Maxwell-Boltzmann velocity sampling.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

User-specified number of Kelvin.


RECOMMENDATION:

This variable is only useful in conjunction with AIMD_INIT_VELOC = THERMAL. Note that the simulations are run at constant energy, rather than constant temperature, so the mean nuclear kinetic energy will fluctuate in the course of the simulation.


AIMD_THERMOSTAT

Applies thermostatting to AIMD trajectories.


TYPE:

INTEGER


DEFAULT:

none


OPTIONS:

LANGEVIN

Stochastic, white-noise Langevin thermostat

NOSE_HOOVER

Time-reversible, Nosé-Hoovery chain thermostat


RECOMMENDATION:

Use either thermostat for sampling the canonical (NVT) ensemble.


AIMD_TIME_STEP_CONVERSION

Modifies the molecular dynamics time step to increase granularity.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$n$

The molecular dynamics time step is TIME_STEP/$n$ a.u.


RECOMMENDATION:

None


ANHAR_SEL

Select a subset of normal modes for subsequent anharmonic frequency analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE

Use all normal modes


OPTIONS:

TRUE

Select subset of normal modes


RECOMMENDATION:

None


ANHAR

Performing various nuclear vibrational theory (TOSH, VPT2, VCI) calculations to obtain vibrational anharmonic frequencies.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Carry out the anharmonic frequency calculation.

FALSE

Do harmonic frequency calculation.


RECOMMENDATION:

Since this calculation involves the third and fourth derivatives at the minimum of the potential energy surface, it is recommended that the GEOM_OPT_TOL_DISPLACEMENT, GEOM_OPT_TOL_GRADIENT and GEOM_OPT_TOL_ENERGY tolerances are set tighter. Note that VPT2 calculations may fail if the system involves accidental degenerate resonances. See the VCI $rem variable for more details about increasing the accuracy of anharmonic calculations.


AO2MO_DISK

Sets the amount of disk space (in megabytes) available for MP2 calculations.


TYPE:

INTEGER


DEFAULT:

2000

Corresponding to 2000 Mb.


OPTIONS:

$n$

User-defined number of megabytes.


RECOMMENDATION:

Should be set as large as possible, discussed in Section 6.4.1.


ARI_R0

Determines the value of the inner fitting radius (in Ångstroms)


TYPE:

INTEGER


DEFAULT:

4

A value of 4 Å will be added to the atomic van der Waals radius.


OPTIONS:

$n$

User defined radius.


RECOMMENDATION:

For some systems the default value may be too small and the calculation will become unstable.


ARI_R1

Determines the value of the outer fitting radius (in Ångstroms)


TYPE:

INTEGER


DEFAULT:

5

A value of 5 Å will be added to the atomic van der Waals radius.


OPTIONS:

$n$

User defined radius.


RECOMMENDATION:

For some systems the default value may be too small and the calculation will become unstable. This value also determines, in part, the smoothness of the potential energy surface.


ARI

Toggles the use of the atomic resolution-of-the-identity (ARI) approximation.


TYPE:

LOGICAL


DEFAULT:

FALSE

ARI will not be used by default for an RI-JK calculation.


OPTIONS:

TRUE

Turn on ARI.


RECOMMENDATION:

For large (especially 1D and 2D) molecules the approximation may yield significant improvements in Fock evaluation time.


AUX_BASIS

Sets the auxiliary basis set to be used


TYPE:

STRING


DEFAULT:

No default auxiliary basis set


OPTIONS:

General, Gen

User-defined. As for BASIS

Symbol

Use standard auxiliary basis sets as in the table below

Mixed

Use a combination of different basis sets


RECOMMENDATION:

Consult literature and EMSL Basis Set Exchange to aid your selection.


BASIS2

Sets the small basis set to use in basis set projection.


TYPE:

STRING


DEFAULT:

No second basis set default.


OPTIONS:

Symbol. Use standard basis sets as per Chapter 8.

BASIS2_GEN

General BASIS2

BASIS2_MIXED

Mixed BASIS2


RECOMMENDATION:

BASIS2 should be smaller than BASIS. There is little advantage to using a basis larger than a minimal basis when BASIS2 is used for initial guess purposes. Larger, standardized BASIS2 options are available for dual-basis calculations (see Section 4.7).


BASISPROJTYPE

Determines which method to use when projecting the density matrix of BASIS2


TYPE:

STRING


DEFAULT:

FOPPROJECTION (when DUAL_BASIS_ENERGY=false)

OVPROJECTION (when DUAL_BASIS_ENERGY=true)


OPTIONS:

FOPPROJECTION

Construct the Fock matrix in the second basis

OVPROJECTION

Projects MOs from BASIS2 to BASIS.


RECOMMENDATION:

None


BASIS_LIN_DEP_THRESH

Sets the threshold for determining linear dependence in the basis set


TYPE:

INTEGER


DEFAULT:

6

Corresponding to a threshold of $10^{-6}$


OPTIONS:

$n$

Sets the threshold to $10^{-n}$


RECOMMENDATION:

Set to 5 or smaller if you have a poorly behaved SCF and you suspect linear dependence in you basis set. Lower values (larger thresholds) may affect the accuracy of the calculation.


BASIS

Specifies the basis sets to be used.


TYPE:

STRING


DEFAULT:

No default basis set


OPTIONS:

General, Gen

User defined ($basis keyword required).

Symbol

Use standard basis sets as per Chapter 8.

Mixed

Use a mixture of basis sets (see Chapter 8).


RECOMMENDATION:

Consult literature and reviews to aid your selection.


BOYSCALC

Specifies the Boys localized orbitals are to be calculated


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not perform localize the occupied space.

1

Allow core-valence mixing in Boys localization.

2

Localize core and valence separately.


RECOMMENDATION:

None


BOYS_CIS_NUMSTATE

Define how many states to mix with Boys localized diabatization. These states must be specified in the $localized_diabatization section.


TYPE:

INTEGER


DEFAULT:

0

Do not perform Boys localized diabatization.


OPTIONS:

2 to N where N is the number of CIS states requested (CIS_N_ROOTS)


RECOMMENDATION:

It is usually not wise to mix adiabatic states that are separated by more than a few eV or a typical reorganization energy in solvent.


CAGE_CHARGE

Defines the total charge of the cage.


TYPE:

INTEGER


DEFAULT:

400

Add a cage charged +4e.


OPTIONS:

$n$

Total charge of the cage is $n$/100 a.u.


RECOMMENDATION:

None


CAGE_POINTS

Defines number of point charges for the spherical cage.


TYPE:

INTEGER


DEFAULT:

100


OPTIONS:

$n$

Number of point charges to use.


RECOMMENDATION:

None


CAGE_RADIUS

Defines radius of the charged cage.


TYPE:

INTEGER


DEFAULT:

225


OPTIONS:

$n$

radius is $n$/100 Å.


RECOMMENDATION:

None


CALC_NAC

Whether or not non-adiabatic couplings will be calculated for the EOM-CC, CIS, and TDDFT wave functions.


TYPE:

INTEGER


DEFAULT:

0 (do not compute NAC)


OPTIONS:

1

NYI for EOM-CC

2

Compute NACs using Szalay’s approach (this what needs to be specified for EOM-CC).


RECOMMENDATION:

Additional response equations will be solved and gradients for all EOM states and for summed states will be computed, which increases the cost of calculations. Request only when needed and do not ask for too many EOM states.


CALC_SOC

Whether or not the spin-orbit couplings between CC/EOM/ADC/CIS/TDDFT electronic states will be calculated. In the CC/EOM-CC suite, by default the couplings are calculated between the CCSD reference and the EOM-CCSD target states. In order to calculate couplings between EOM states, CC_STATE_TO_OPT must specify the initial EOM state.


TYPE:

LOGICAL


DEFAULT:

FALSE (no spin-orbit couplings will be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

One-electron and mean-field two-electron SOCs will be computed by default. To enable full two-electron SOCs, two-particle EOM properties must be turned on (see CC_EOM_PROP_TE).


CALC_SOC

Controls whether to calculate the SOC constants for EOM-CC, ADC, TDDFT/TDA and TDDFT.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform the SOC calculation.

TRUE

Perform the SOC calculation.


RECOMMENDATION:

None


CCVB_GUESS

Specifies the initial guess for CCVB calculations


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

1

Standard GVBMAN guess (orbital localization via GVB_LOCAL + Sano procedure).

2

Use orbitals from previous GVBMAN calculation, along with SCF_GUESS = read.

3

Convert UHF orbitals into pairing VB form.


RECOMMENDATION:

Option 1 is the most useful overall. The success of GVBMAN methods is often dependent on localized orbitals, and this guess shoots for these. Option 2 is useful for comparing results to other GVBMAN methods, or if other GVBMAN methods are able to obtain a desired result more efficiently. Option 3 can be useful for bond-breaking situations when a pertinent UHF solution has been found. It works best for small systems, or if the unrestriction is a local phenomenon within a larger molecule. If the unrestriction is non-local and the system is large, this guess will often produce a solution that is not the global minimum. Any UHF solution has a certain number of pairs that are unrestricted, and this will be output by the program. If GVB_N_PAIRS exceeds this number, the standard GVBMAN initial-guess procedure will be used to obtain a guess for the excess pairs


CCVB_METHOD

Optionally modifies the basic CCVB method


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

1

Standard CCVB model

3

Independent electron pair approximation (IEPA) to CCVB

4

Variational PP (the CCVB reference energy)


RECOMMENDATION:

Option 1 is generally recommended. Option 4 is useful for preconditioning, and for obtaining localized-orbital solutions, which may be used in subsequent calculations. It is also useful for cases in which the regular GVBMAN PP code becomes variationally unstable. Option 3 is a simple independent-amplitude approximation to CCVB. It avoids the cubic-scaling amplitude equations of CCVB, and also is able to reach the correct dissociation energy for any molecular system (unlike regular CCVB which does so only for cases in which UHF can reach a correct dissociate limit). However the IEPA approximation to CCVB is sometimes variationally unstable, which we have yet to observe in regular CCVB.


CC_BACKEND

Used to specify the computational back-end of CCMAN2.


TYPE:

STRING


DEFAULT:

VM

Default shared-memory disk-based back-end


OPTIONS:

XM

libxm shared-memory disk-based back-end

CTF

Distributed-memory back-end for MPI jobs


RECOMMENDATION:

Use XM for large jobs with limited memory or when the performance of the default disk-based back-end is not satisfactory, CTF for MPI jobs


CC_CANONIZE_FINAL

Whether to semi-canonicalize orbitals at the end of the ground state calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE

unless required


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Should not normally have to be altered.


CC_CANONIZE_FREQ

The orbitals will be semi-canonicalized every $n$ theta resets. The thetas (orbital rotation angles) are reset every CC_RESET_THETA iterations. The counting of iterations differs for active space (VOD, VQCCD) calculations, where the orbitals are always canonicalized at the first theta-reset.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

User-defined integer


RECOMMENDATION:

Smaller values can be tried in cases that do not converge.


CC_CANONIZE

Whether to semi-canonicalize orbitals at the start of the calculation (i.e. Fock matrix is diagonalized in each orbital subspace)


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Should not normally have to be altered.


CC_CONVERGENCE

Overall convergence criterion for the coupled-cluster codes. This is designed to ensure at least $n$ significant digits in the calculated energy, and automatically sets the other convergence-related variables (CC_E_CONV, CC_T_CONV, CC_THETA_CONV, CC_THETA_GRAD_CONV) [$10^{-n}$].


TYPE:

INTEGER


DEFAULT:

6

Energies.

7

Gradients.


OPTIONS:

$n$

Corresponding to $10^{-n}$ convergence criterion. Amplitude convergence is set

 

automatically to match energy convergence.


RECOMMENDATION:

Use the default


CC_DIIS12_SWITCH

When to switch from DIIS2 to DIIS1 procedure, or when DIIS2 procedure is required to generate DIIS guesses less frequently. Total value of DIIS error vector must be less than $10^{-n}$, where $n$ is the value of this option.


TYPE:

INTEGER


DEFAULT:

5


OPTIONS:

$n$

User-defined integer


RECOMMENDATION:

None


CC_DIIS_FREQ

DIIS extrapolation will be attempted every n iterations. However, DIIS2 will be attempted every iteration while total error vector exceeds CC_DIIS12_SWITCH. DIIS1 cannot generate guesses more frequently than every 2 iterations.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$N$

User-defined integer


RECOMMENDATION:

None


CC_DIIS_MAX_OVERLAP

DIIS extrapolations will not begin until square root of the maximum element of the error overlap matrix drops below this value.


TYPE:

DOUBLE


DEFAULT:

100

Corresponding to 1.0


OPTIONS:

$abcde$

Integer code is mapped to $abc\times 10^{-de}$


RECOMMENDATION:

None


CC_DIIS_MIN_OVERLAP

The DIIS procedure will be halted when the square root of smallest element of the error overlap matrix is less than $10^{-n}$, where $n$ is the value of this option. Small values of the B matrix mean it will become near-singular, making the DIIS equations difficult to solve.


TYPE:

INTEGER


DEFAULT:

11


OPTIONS:

$n$

User-defined integer


RECOMMENDATION:

None


CC_DIIS_SIZE

Specifies the maximum size of the DIIS space.


TYPE:

INTEGER


DEFAULT:

7


OPTIONS:

$n$

User-defined integer


RECOMMENDATION:

Larger values involve larger amounts of disk storage.


CC_DIIS_START

Iteration number when DIIS is turned on. Set to a large number to disable DIIS.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

$n$

User-defined


RECOMMENDATION:

Occasionally DIIS can cause optimized orbital coupled-cluster calculations to diverge through large orbital changes. If this is seen, DIIS should be disabled.


CC_DIIS

Specify the version of Pulay’s Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator to be used in the coupled-cluster code.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Activates procedure 2 initially, and procedure 1 when gradients are smaller

 

than DIIS12_SWITCH.

1

Uses error vectors defined as differences between parameter vectors from

 

successive iterations. Most efficient near convergence.

2

Error vectors are defined as gradients scaled by square root of the

 

approximate diagonal Hessian. Most efficient far from convergence.


RECOMMENDATION:

DIIS1 can be more stable. If DIIS problems are encountered in the early stages of a calculation (when gradients are large) try DIIS1.


CC_DIRECT_RI

Controls use of RI and Cholesky integrals in conventional (undecomposed) form


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

use all integrals in decomposed format

TRUE

transform all RI or Cholesky integral back to conventional format


RECOMMENDATION:

By default all integrals are used in decomposed format allowing significant reduction of memory use. If all integrals are transformed back (TRUE option) no memory reduction is achieved and decomposition error is introduced, however, the integral transformation is performed significantly faster and conventional CC/EOM algorithms are used.


CC_DOV_THRESH

Specifies minimum allowed values for the coupled-cluster energy denominators. Smaller values are replaced by this constant during early iterations only, so the final results are unaffected, but initial convergence is improved when the guess is poor.


TYPE:

INTEGER


DEFAULT:

$2502$

Corresponding to 0.25


OPTIONS:

$abcde$

Integer code is mapped to $abc\times 10^{-de}$


RECOMMENDATION:

Increase to 0.5 or 0.75 for non convergent coupled-cluster calculations.


CC_DO_DYSON_EE

Whether excited-state or spin-flip state Dyson orbitals will be calculated for EOM-IP/EA-CCSD calculations with CCMAN.


TYPE:

LOGICAL


DEFAULT:

FALSE (the option must be specified to run this calculation)


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

none


CC_DO_DYSON

CCMAN2: starts all types of Dyson orbitals calculations. Desired type is determined by requesting corresponding EOM-XX transitions CCMAN: whether the reference-state Dyson orbitals will be calculated for EOM-IP/EA-CCSD calculations.


TYPE:

LOGICAL


DEFAULT:

FALSE (the option must be specified to run this calculation)


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

none


CC_EOM_2PA

Whether or not the transition moments and cross-sections for two-photon absorption will be calculated. By default, the transition moments are calculated between the CCSD reference and the EOM-CCSD target states. In order to calculate transition moments between a set of EOM-CCSD states and another EOM-CCSD state, the CC_STATE_TO_OPT must be specified for this state. If 2PA NTO analysis is requested, the CC_EOM_2PA value is redundant as long as CC_EOM_2PA $> 0 $.


TYPE:

INTEGER


DEFAULT:

0 (do not compute 2PA transition moments)


OPTIONS:

1

Compute 2PA using the fastest algorithm (use $\tilde{\sigma }$-intermediates for canonical

 

and $\sigma $-intermediates for RI/CD response calculations).

2

Use $\sigma $-intermediates for 2PA response equation calculations.

3

Use $\tilde{\sigma }$-intermediates for 2PA response equation calculations.


RECOMMENDATION:

Additional response equations (6 for each target state) will be solved, which increases the cost of calculations. The cost of 2PA moments is about 10 times that of energy calculation. Use the default algorithm. Setting CC_EOM_2PA $> 0 $ turns on CC_TRANS_PROP.


CC_EOM_PROP

Whether or not the non-relaxed (expectation value) one-particle EOM-CCSD target state properties will be calculated. The properties currently include permanent dipole moment, the second moments $\ensuremath{\langle }X^2\ensuremath{\rangle }$, $\ensuremath{\langle }Y^2\ensuremath{\rangle }$, and $\ensuremath{\langle }Z^2\ensuremath{\rangle }$ of electron density, and the total $\ensuremath{\langle }R^2\ensuremath{\rangle }= \ensuremath{\langle }X^2\ensuremath{\rangle }+\ensuremath{\langle }Y^2\ensuremath{\rangle }+\ensuremath{\langle }Z^2\ensuremath{\rangle }$ (in atomic units). Incompatible with JOBTYPE=FORCE, OPT, FREQ.


TYPE:

LOGICAL


DEFAULT:

FALSE (no one-particle properties will be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

Additional equations (EOM-CCSD equations for the left eigenvectors) need to be solved for properties, approximately doubling the cost of calculation for each irrep. The cost of the one-particle properties calculation itself is low. The one-particle density of an EOM-CCSD target state can be analyzed with NBO or libwfa packages by specifying the state with CC_STATE_TO_OPT and requesting NBO = TRUE and CC_EOM_PROP = TRUE.


CC_E_CONV

Convergence desired on the change in total energy, between iterations.


TYPE:

INTEGER


DEFAULT:

10


OPTIONS:

$n$

$10^{-n}$ convergence criterion.


RECOMMENDATION:

None


CC_FNO_THRESH

Initialize the FNO truncation and sets the threshold to be used for both cutoffs (OCCT and POVO)


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

range

0000-10000

$abcd$

Corresponding to $ab.cd$%


RECOMMENDATION:

None


CC_FNO_USEPOP

Selection of the truncation scheme


TYPE:

INTEGER


DEFAULT:

1

OCCT


OPTIONS:

0

POVO


RECOMMENDATION:

None


CC_FULLRESPONSE

Fully relaxed properties (including orbital relaxation terms) will be computed. The variable CC_REF_PROP must be also set to TRUE.


TYPE:

LOGICAL


DEFAULT:

FALSE

(no orbital response will be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

Not available for non UHF/RHF references and for the methods that do not have analytic gradients (e.g., QCISD).


CC_HESS_THRESH

Minimum allowed value for the orbital Hessian. Smaller values are replaced by this constant.


TYPE:

DOUBLE


DEFAULT:

102

Corresponding to 0.01


OPTIONS:

$abcde$

Integer code is mapped to $abc\times 10^{-de}$


RECOMMENDATION:

None


CC_INCL_CORE_CORR

Whether to include the correlation contribution from frozen core orbitals in non iterative (2) corrections, such as OD(2) and CCSD(2).


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

FALSE


RECOMMENDATION:

Use the default unless no core-valence or core correlation is desired (e.g., for comparison with other methods or because the basis used cannot describe core correlation).


CC_ITERATE_ON

In active space calculations, use a “mixed” iteration procedure if the value is greater than 0. Then if the RMS orbital gradient is larger than the value of CC_THETA_GRAD_THRESH, micro-iterations will be performed to converge the occupied-virtual mixing angles for the current active space. The maximum number of space iterations is given by this option.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Up to $n$ occupied-virtual iterations per overall cycle


RECOMMENDATION:

Can be useful for non-convergent active space calculations


CC_ITERATE_OV

In active space calculations, use a “mixed” iteration procedure if the value is greater than 0. Then, if the RMS orbital gradient is larger than the value of CC_THETA_GRAD_THRESH, micro-iterations will be performed to converge the occupied-virtual mixing angles for the current active space. The maximum number of such iterations is given by this option.


TYPE:

INTEGER


DEFAULT:

0

No “mixed” iterations


OPTIONS:

$n$

Up to $n$ occupied-virtual iterations per overall cycle


RECOMMENDATION:

Can be useful for non-convergent active space calculations.


CC_MAX_ITER

Maximum number of iterations to optimize the coupled-cluster energy.


TYPE:

INTEGER


DEFAULT:

200


OPTIONS:

$n$

up to $n$ iterations to achieve convergence.


RECOMMENDATION:

None


CC_MEMORY

Specifies the maximum size, in Mb, of the buffers for in-core storage of block-tensors in CCMAN and CCMAN2.


TYPE:

INTEGER


DEFAULT:

50% of MEM_TOTAL. If MEM_TOTAL is not set, use 1.5 Gb. A minimum of

192 Mb is hard-coded.


OPTIONS:

$n$

Integer number of Mb


RECOMMENDATION:

Larger values can give better I/O performance and are recommended for systems with large memory (add to your .qchemrc file. When running CCMAN2 exclusively on a node, CC_MEMORY should be set to 75–80% of the total available RAM. )


CC_MP2NO_GRAD

If CC_MP2NO_GUESS is TRUE, what kind of one-particle density matrix is used to make the guess orbitals?


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

1 PDM from MP2 gradient theory.

FALSE

1 PDM expanded to 2$^{\ensuremath{\mathrm{nd}}}$ order in perturbation theory.


RECOMMENDATION:

The two definitions give generally similar performance.


CC_MP2NO_GUESS

Will guess orbitals be natural orbitals of the MP2 wave function? Alternatively, it is possible to use an effective one-particle density matrix to define the natural orbitals.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Use natural orbitals from an MP2 one-particle density matrix (see CC_MP2NO_GRAD).

FALSE

Use current molecular orbitals from SCF.


RECOMMENDATION:

None


CC_ORBS_PER_BLOCK

Specifies target (and maximum) size of blocks in orbital space.


TYPE:

INTEGER


DEFAULT:

16


OPTIONS:

$n$

Orbital block size of $n$ orbitals.


RECOMMENDATION:

None


CC_POL

Whether or not the static polarizability for the CCSD wave function will be calculated.


TYPE:

LOGICAL


DEFAULT:

FALSE (CCSD static polarizability will not be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

Static polarizabilities are expensive since they require solving three additional response equations. Do no request this property unless you need it.


CC_PRECONV_FZ

In active space methods, whether to pre-converge other wave function variables for fixed initial guess of active space.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

No pre-iterations before active space optimization begins.

$n$

Maximum number of pre-iterations via this procedure.


RECOMMENDATION:

None


CC_PRECONV_T2Z_EACH

Whether to pre-converge the cluster amplitudes before each change of the orbitals in optimized orbital coupled-cluster methods. The maximum number of iterations in this pre-convergence procedure is given by the value of this parameter.


TYPE:

INTEGER


DEFAULT:

0

(FALSE)


OPTIONS:

0

No pre-convergence before orbital optimization.

$n$

Up to $n$ iterations in this pre-convergence procedure.


RECOMMENDATION:

A very slow last resort option for jobs that do not converge.


CC_PRECONV_T2Z

Whether to pre-converge the cluster amplitudes before beginning orbital optimization in optimized orbital cluster methods.


TYPE:

INTEGER


DEFAULT:

0

(FALSE)

10

If CC_RESTART, CC_RESTART_NO_SCF or CC_MP2NO_GUESS are TRUE


OPTIONS:

0

No pre-convergence before orbital optimization.

$n$

Up to $n$ iterations in this pre-convergence procedure.


RECOMMENDATION:

Experiment with this option in cases of convergence failure.


CC_PRINT

Controls the output from post-MP2 coupled-cluster module of Q-Chem


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$0-7$

higher values can lead to deforestation…


RECOMMENDATION:

Increase if you need more output and don’t like trees


CC_QCCD_THETA_SWITCH

QCCD calculations switch from OD to QCCD when the rotation gradient is below this threshold [$10^{-n}$]


TYPE:

INTEGER


DEFAULT:

2

$10^{-2}$ switchover


OPTIONS:

$n$

$10^{-n}$ switchover


RECOMMENDATION:

None


CC_REF_PROP_TE

Request for calculation of non-relaxed two-particle CCSD properties. The two-particle properties currently include $\ensuremath{\langle }S^2\ensuremath{\rangle }$. The one-particle properties also will be calculated, since the additional cost of the one-particle properties calculation is inferior compared to the cost of $\ensuremath{\langle }S^2\ensuremath{\rangle }$. The variable CC_REF_PROP must be also set to TRUE.


TYPE:

LOGICAL


DEFAULT:

FALSE

(no two-particle properties will be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

The two-particle properties are computationally expensive, since they require calculation and use of the two-particle density matrix (the cost is approximately the same as the cost of an analytic gradient calculation). Do not request the two-particle properties unless you really need them.


CC_REF_PROP

Whether or not the non-relaxed (expectation value) or full response (including orbital relaxation terms) one-particle CCSD properties will be calculated. The properties currently include permanent dipole moment, the second moments $\ensuremath{\langle }X^2\ensuremath{\rangle }$, $\ensuremath{\langle }Y^2\ensuremath{\rangle }$, and $\ensuremath{\langle }Z^2\ensuremath{\rangle }$ of electron density, and the total $\ensuremath{\langle }R^2\ensuremath{\rangle }= \ensuremath{\langle }X^2\ensuremath{\rangle }+\ensuremath{\langle }Y^2\ensuremath{\rangle }+\ensuremath{\langle }Z^2\ensuremath{\rangle }$ (in atomic units). Incompatible with JOBTYPE=FORCE, OPT, FREQ.


TYPE:

LOGICAL


DEFAULT:

FALSE

(no one-particle properties will be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

Additional equations need to be solved (lambda CCSD equations) for properties with the cost approximately the same as CCSD equations. Use the default if you do not need properties. The cost of the properties calculation itself is low. The CCSD one-particle density can be analyzed with NBO package by specifying NBO=TRUE, CC_REF_PROP=TRUE and JOBTYPE=FORCE.


CC_RESET_THETA

The reference MO coefficient matrix is reset every n iterations to help overcome problems associated with the theta metric as theta becomes large.


TYPE:

INTEGER


DEFAULT:

15


OPTIONS:

$n$

$n$ iterations between resetting orbital rotations to zero.


RECOMMENDATION:

None


CC_RESTART_NO_SCF

Should an optimized orbital coupled cluster calculation begin with optimized orbitals from a previous calculation? When TRUE, molecular orbitals are initially orthogonalized, and CC_PRECONV_T2Z and CC_CANONIZE are set to TRUE while other guess options are set to FALSE


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

None


CC_RESTART

Allows an optimized orbital coupled cluster calculation to begin with an initial guess for the orbital transformation matrix U other than the unit vector. The scratch file from a previous run must be available for the U matrix to be read successfully.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Use unit initial guess.

TRUE

Activates CC_PRECONV_T2Z, CC_CANONIZE, and

 

turns off CC_MP2NO_GUESS


RECOMMENDATION:

Useful for restarting a job that did not converge, if files were saved.


CC_RESTR_AMPL

Controls the restriction on amplitudes is there are restricted orbitals


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

0

All amplitudes are in the full space

1

Amplitudes are restricted, if there are restricted orbitals


RECOMMENDATION:

None


CC_RESTR_TRIPLES

Controls which space the triples correction is computed in


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Triples are computed in the full space

1

Triples are restricted to the active space


RECOMMENDATION:

None


CC_REST_AMPL

Forces the integrals, $T$, and $R$ amplitudes to be determined in the full space even though the CC_REST_OCC and CC_REST_VIR keywords are used.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

FALSE

Do apply restrictions

TRUE

Do not apply restrictions


RECOMMENDATION:

None


CC_REST_OCC

Sets the number of restricted occupied orbitals including active core occupied orbitals.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Restrict $n$ energetically lowest occupied orbitals to correspond to the active core space.


RECOMMENDATION:

Example: cytosine with the molecular formula C$_4$H$_5$N$_3$O includes one oxygen atom. To calculate O 1s core-excited states, $n$ has to be set to 1, because the 1s orbital of oxygen is the energetically lowest. To obtain the N 1s core excitations, the integer $n$ has to be set to 4, because the 1s orbital of the oxygen atom is included as well, since it is energetically below the three 1s orbitals of the nitrogen atoms. Accordingly, to simulate the C 1s spectrum of cytosine, $n$ must be set to 8.


CC_REST_TRIPLES

Restricts $R_3$ amplitudes to the active space, i.e., one electron should be removed from the active occupied orbital and one electron should be added to the active virtual orbital.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

1

Applies the restrictions


RECOMMENDATION:

None


CC_REST_VIR

Sets the number of restricted virtual orbitals including frozen virtual orbitals.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Restrict $n$ virtual orbitals.


RECOMMENDATION:

None


CC_SCALE_AMP

If not 0, scales down the step for updating coupled-cluster amplitudes in cases of problematic convergence.


TYPE:

INTEGER


DEFAULT:

0

no scaling


OPTIONS:

$abcd$

Integer code is mapped to $abcd\times 10^{-2}$, e.g., $90$ corresponds to 0.9


RECOMMENDATION:

Use 0.9 or 0.8 for non convergent coupled-cluster calculations.


CC_STATE_TO_OPT

Specifies which state to optimize.


TYPE:

INTEGER ARRAY


DEFAULT:

None


OPTIONS:

[$i$,$j$]

optimize the $j$th state of the $i$th irrep.


RECOMMENDATION:

None


CC_SYMMETRY

Activates point-group symmetry in the ADC calculation.


TYPE:

LOGICAL


DEFAULT:

TRUE

If the system possesses any point-group symmetry.


OPTIONS:

TRUE

Employ point-group symmetry

FALSE

Do not use point-group symmetry


RECOMMENDATION:

None


CC_THETA_CONV

Convergence criterion on the RMS difference between successive sets of orbital rotation angles [$10^{-n}$].


TYPE:

INTEGER


DEFAULT:

5

Energies

6

Gradients


OPTIONS:

$n$

$10^{-n}$ convergence criterion.


RECOMMENDATION:

Use default


CC_THETA_GRAD_CONV

Convergence desired on the RMS gradient of the energy with respect to orbital rotation angles [$10^{-n}$].


TYPE:

INTEGER


DEFAULT:

7

Energies

8

Gradients


OPTIONS:

$n$

$10^{-n}$ convergence criterion.


RECOMMENDATION:

Use default


CC_THETA_GRAD_THRESH

RMS orbital gradient threshold [$10^{-n}$] above which “mixed iterations” are performed in active space calculations if CC_ITERATE_OV is TRUE.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$n$

$10^{-n}$ threshold.


RECOMMENDATION:

Can be made smaller if convergence difficulties are encountered.


CC_THETA_STEPSIZE

Scale factor for the orbital rotation step size. The optimal rotation steps should be approximately equal to the gradient vector.


TYPE:

INTEGER


DEFAULT:

$100$

Corresponding to 1.0


OPTIONS:

$abcde$

Integer code is mapped to $abc\times 10^{-de}$

 

If the initial step is smaller than 0.5, the program will increase step

 

when gradients are smaller than the value of THETA_GRAD_THRESH,

 

up to a limit of 0.5.


RECOMMENDATION:

Try a smaller value in cases of poor convergence and very large orbital gradients. For example, a value of 01001 translates to 0.1


CC_TRANS_PROP

Whether or not the transition dipole moment (in atomic units) and oscillator strength for the EOM-CCSD target states will be calculated. By default, the transition dipole moment is calculated between the CCSD reference and the EOM-CCSD target states. In order to calculate transition dipole moment between a set of EOM-CCSD states and another EOM-CCSD state, the CC_STATE_TO_OPT must be specified for this state.


TYPE:

INTEGER


DEFAULT:

0 (no transition properties will be calculated)


OPTIONS:

1 (calculate transition properties between all computed EOM state and the reference state)

2 (calculate transition properties between all pairs of EOM states)


RECOMMENDATION:

NONE


Additional equations (for the left EOM-CCSD eigenvectors plus lambda CCSD equations in case if transition properties between the CCSD reference and EOM-CCSD target states are requested) need to be solved for transition properties, approximately doubling the computational cost. The cost of the transition properties calculation itself is low.

CC_T_CONV

Convergence criterion on the RMS difference between successive sets of coupled-cluster doubles amplitudes [$10^{-n}$]


TYPE:

INTEGER


DEFAULT:

8

energies

10

gradients


OPTIONS:

$n$

$10^{-n}$ convergence criterion.


RECOMMENDATION:

Use default


CC_Z_CONV

Convergence criterion on the RMS difference between successive doubles $Z$-vector amplitudes [$10^{-n}$].


TYPE:

INTEGER


DEFAULT:

8

Energies

10

Gradients


OPTIONS:

$n$

$10^{-n}$ convergence criterion.


RECOMMENDATION:

Use Default


CDFTCI_PRINT

Controls level of output from CDFT-CI procedure to Q-Chem output file.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Only print energies and coefficients of CDFT-CI final states

1

Level 0 plus CDFT-CI overlap, Hamiltonian, and population matrices

2

Level 1 plus eigenvectors and eigenvalues of the CDFT-CI population matrix

3

Level 2 plus promolecule orbital coefficients and energies


RECOMMENDATION:

Level 3 is primarily for program debugging; levels 1 and 2 may be useful for analyzing the coupling elements


CDFTCI_RESTART

To be used in conjunction with CDFTCI_STOP, this variable causes CDFT-CI to read already-converged states from disk and begin SCF convergence on later states. Note that the same $cdft section must be used for the stopped calculation and the restarted calculation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Start calculations on state $n+1$


RECOMMENDATION:

Use this setting in conjunction with CDFTCI_STOP.


CDFTCI_SKIP_PROMOLECULES

Skips promolecule calculations and allows fractional charge and spin constraints to be specified directly.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Standard CDFT-CI calculation is performed.

TRUE

Use the given charge/spin constraints directly, with no promolecule calculations.


RECOMMENDATION:

Setting to TRUE can be useful for scanning over constraint values.


CDFTCI_STOP

The CDFT-CI procedure involves performing independent SCF calculations on distinct constrained states. It sometimes occurs that the same convergence parameters are not successful for all of the states of interest, so that a CDFT-CI calculation might converge one of these diabatic states but not the next. This variable allows a user to stop a CDFT-CI calculation after a certain number of states have been converged, with the ability to restart later on the next state, with different convergence options.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Stop after converging state $n$ (the first state is state $1$)

$0$

Do not stop early


RECOMMENDATION:

Use this setting if some diabatic states converge but others do not.


CDFTCI_SVD_THRESH

By default, a symmetric orthogonalization is performed on the CDFT-CI matrix before diagonalization. If the CDFT-CI overlap matrix is nearly singular (i.e., some of the diabatic states are nearly degenerate), then this orthogonalization can lead to numerical instability. When computing $\mathbf{S}^{-1/2}$, eigenvalues smaller than $10^{-\mathrm{CDFTCI\_ SVD\_ THRESH}}$ are discarded.


TYPE:

INTEGER


DEFAULT:

4


OPTIONS:

$n$

for a threshold of $10^{-n}$.


RECOMMENDATION:

Can be decreased if numerical instabilities are encountered in the final diagonalization.


CDFTCI

Initiates a constrained DFT-configuration interaction calculation


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform a CDFT-CI Calculation

FALSE

No CDFT-CI


RECOMMENDATION:

Set to TRUE if a CDFT-CI calculation is desired.


CDFT_BECKE_POP

Whether the calculation should print the Becke atomic charges at convergence


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Print Populations

FALSE

Do not print them


RECOMMENDATION:

Use the default. Note that the Mulliken populations printed at the end of an SCF run will not typically add up to the prescribed constraint value. Only the Becke populations are guaranteed to satisfy the user-specified constraints.


CDFT_CRASHONFAIL

Whether the calculation should crash or not if the constraint iterations do not converge.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Crash if constraint iterations do not converge.

FALSE

Do not crash.


RECOMMENDATION:

Use the default.


CDFT_LAMBDA_MODE

Allows CDFT potentials to be specified directly, instead of being determined as Lagrange multipliers.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Standard CDFT calculations are used.

TRUE

Instead of specifying target charge and spin constraints, use the values

 

from the input deck as the value of the Becke weight potential


RECOMMENDATION:

Should usually be set to FALSE. Setting to TRUE can be useful to scan over different strengths of charge or spin localization, as convergence properties are improved compared to regular CDFT(-CI) calculations.


CDFT_POP

Sets the charge partitioning scheme for cDFT in SAPT/cDFT


TYPE:

STRING


DEFAULT:

FBH


OPTIONS:

FBH

Fragment-Based Hirshfeld partitioning

BECKE

Atomic Becke partitioning


RECOMMENDATION:

None


CDFT_POSTDIIS

Controls whether the constraint is enforced after DIIS extrapolation.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Enforce constraint after DIIS

FALSE

Do not enforce constraint after DIIS


RECOMMENDATION:

Use the default unless convergence problems arise, in which case it may be beneficial to experiment with setting CDFT_POSTDIIS to FALSE. With this option set to TRUE, energies should be variational after the first iteration.


CDFT_PREDIIS

Controls whether the constraint is enforced before DIIS extrapolation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Enforce constraint before DIIS

FALSE

Do not enforce constraint before DIIS


RECOMMENDATION:

Use the default unless convergence problems arise, in which case it may be beneficial to experiment with setting CDFT_PREDIIS to TRUE. Note that it is possible to enforce the constraint both before and after DIIS by setting both CDFT_PREDIIS and CDFT_POSTDIIS to TRUE.


CDFT_THRESH

Threshold that determines how tightly the constraint must be satisfied.


TYPE:

INTEGER


DEFAULT:

5


OPTIONS:

N

Constraint is satisfied to within $10^{-N}$.


RECOMMENDATION:

Use the default unless problems occur.


CDFT

Initiates a constrained DFT calculation


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform a Constrained DFT Calculation

FALSE

No Density Constraint


RECOMMENDATION:

Set to TRUE if a Constrained DFT calculation is desired.


CD_ALGORITHM

Determines the algorithm for MP2 integral transformations.


TYPE:

STRING


DEFAULT:

Program determined.


OPTIONS:

DIRECT

Uses fully direct algorithm (energies only).

SEMI_DIRECT

Uses disk-based semi-direct algorithm.

LOCAL_OCCUPIED

Alternative energy algorithm (see 6.4.1).


RECOMMENDATION:

Semi-direct is usually most efficient, and will normally be chosen by default.


CFMM_ORDER

Controls the order of the multipole expansions in CFMM calculation.


TYPE:

INTEGER


DEFAULT:

15

For single point SCF accuracy

25

For tighter convergence (optimizations)


OPTIONS:

$n$

Use multipole expansions of order $n$


RECOMMENDATION:

Use the default.


CHARGE_CHARGE_REPULSION

The repulsive Coulomb interaction parameter for YinYang atoms.


TYPE:

INTEGER


DEFAULT:

550


OPTIONS:

$n$

Use Q = $n \times 10^{-3}$


RECOMMENDATION:

The repulsive Coulomb potential maintains bond lengths involving YinYang atoms with the potential $V(r) = Q/r$. The default is parameterized for carbon atoms.


CHELPG_DX

Sets the rectangular grid spacing for the traditional Cartesian ChElPG grid or the spacing between concentric Lebedev shells (when the variables CHELPG_HA and CHELPG_H are specified as well).


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$N$

Corresponding to a grid space of $N/20$, in Å.


RECOMMENDATION:

Use the default, which corresponds to the “dense grid” of Breneman and Wiberg,[Breneman and Wiberg(1990)], unless the cost is prohibitive, in which case a larger value can be selected. Note that this default value is set with the Cartesian grid in mind and not the Lebedev grid. In the Lebedev case, a larger value can typically be used.


CHELPG_HA

Sets the Lebedev grid to use for non-hydrogen atoms.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$N$

Corresponding to a number of points in a Lebedev grid (see Section 5.5.1.


RECOMMENDATION:

None.


CHELPG_HEAD

Sets the “head space”[Breneman and Wiberg(1990)] (radial extent) of the ChElPG grid.


TYPE:

INTEGER


DEFAULT:

30


OPTIONS:

$N$

Corresponding to a head space of $N/10$, in Å.


RECOMMENDATION:

Use the default, which is the value recommended by Breneman and Wiberg.[Breneman and Wiberg(1990)]


CHELPG_H

Sets the Lebedev grid to use for hydrogen atoms.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$N$

Corresponding to a number of points in a Lebedev grid.


RECOMMENDATION:

CHELPG_H must always be less than or equal to CHELPG_HA. If it is greater, it will automatically be set to the value of CHELPG_HA.


CHELPG

Controls the calculation of CHELPG charges.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not calculate ChElPG charges.

TRUE

Compute ChElPG charges.


RECOMMENDATION:

Set to TRUE if desired. For large molecules, there is some overhead associated with computing ChElPG charges, especially if the number of grid points is large.


CHILD_MP_ORDERS

The multipole orders included in the prepared FERFs. The last digit specifies how many multipoles to compute, and the digits in the front specify the multipole orders: 2: dipole (D); 3: quadrupole (Q); 4: octopole (O).


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

21

D

232

DQ

2343

DQO


RECOMMENDATION:

Use 232 (DQ) when FERF is needed.


CHILD_MP

Compute FERFs for fragments and use them as the basis for SCFMI calculations.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not compute FERFs (use the full AO span of each fragment).

TRUE

Compute fragment FERFs.


RECOMMENDATION:

Use FERFs to compute polarization energy when large basis sets are used. In an “EDA2" calculation, this $rem variable is set based on the given option automatically.


CHOLESKY_TOL

Tolerance of Cholesky decomposition of two-electron integrals


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

$n$

Corresponds to a tolerance of $10^{-n}$


RECOMMENDATION:

2 - qualitative calculations, 3 - appropriate for most cases, 4 - quantitative (error in total energy typically less than 1 $\mu $hartree)


CISTR_PRINT

Controls level of output.


TYPE:

LOGICAL


DEFAULT:

FALSE

Minimal output.


OPTIONS:

TRUE

Increase output level.


RECOMMENDATION:

None


CIS_AMPL_ANAL

Perform additional analysis of CIS and TDDFT excitation amplitudes, including generation of natural transition orbitals, excited-state multipole moments, and Mulliken analysis of the excited state densities and particle/hole density matrices.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform additional amplitude analysis.

FALSE

Do not perform additional analysis.


RECOMMENDATION:

None


CIS_CONVERGENCE

CIS is considered converged when error is less than $10^{-\ensuremath{\mathrm{CIS\_ CONVERGENCE}}}$


TYPE:

INTEGER


DEFAULT:

6

CIS convergence threshold 10$^{-6}$


OPTIONS:

$n$

Corresponding to $10^{-n}$


RECOMMENDATION:

None


CIS_DER_NUMSTATE

Determines among how many states we calculate non-adiabatic couplings. These states must be specified in the $derivative_coupling section.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not calculate non-adiabatic couplings.

$n$

Calculate $n(n-1)/2$ pairs of non-adiabatic couplings.


RECOMMENDATION:

None.


CIS_DIABATH_DECOMPOSE

Decide whether or not to decompose the diabatic coupling into Coulomb, exchange, and one-electron terms.


TYPE:

LOGICAL


DEFAULT:

FALSE

Do not decompose the diabatic coupling.


OPTIONS:

TRUE


RECOMMENDATION:

These decompositions are most meaningful for electronic excitation transfer processes. Currently, available only for CIS, not for TDDFT diabatic states.


CIS_DYNAMIC_MEM

Controls whether to use static or dynamic memory in CIS and TDDFT calculations.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Partly use static memory

TRUE

Fully use dynamic memory


RECOMMENDATION:

The default control requires static memory (MEM_STATIC) to hold a temporary array whose minimum size is $OV \times \mbox{{\small CIS\_ N\_ ROOTS}}$. For a large calculation, one has to specify a large value for MEM_STATIC, which is not recommended (see Chapter 2). Therefore, it is recommended to use dynamic memory for large calculations.


CIS_GUESS_DISK_TYPE

Determines the type of guesses to be read from disk


TYPE:

INTEGER


DEFAULT:

Nil


OPTIONS:

0

Read triplets only

1

Read triplets and singlets

2

Read singlets only


RECOMMENDATION:

Must be specified if CIS_GUESS_DISK is TRUE.


CIS_GUESS_DISK

Read the CIS guess from disk (previous calculation).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Create a new guess.

TRUE

Read the guess from disk.


RECOMMENDATION:

Requires a guess from previous calculation.


CIS_MOMENTS

Controls calculation of excited-state (CIS or TDDFT) multipole moments


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not calculate excited-state moments.

TRUE

Calculate moments for each excited state.


RECOMMENDATION:

Set to TRUE if excited-state moments are desired. (This is a trivial additional calculation.) The MULTIPOLE_ORDER controls how many multipole moments are printed.


CIS_MULLIKEN

Controls Mulliken and Löwdin population analyses for excited-state particle and hole density matrices.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform particle/hole population analysis.

TRUE

Perform both Mulliken and Löwdin analysis of the particle and hole

 

density matrices for each excited state.


RECOMMENDATION:

Set to TRUE if desired. This represents a trivial additional calculation.


CIS_N_ROOTS

Sets the number of excited state roots to find


TYPE:

INTEGER


DEFAULT:

0

Do not look for any excited states


OPTIONS:

$n$

$n> 0$ Looks for $n$ excited states


RECOMMENDATION:

None


CIS_RELAXED_DENSITY

Use the relaxed CIS density for attachment/detachment density analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not use the relaxed CIS density in analysis.

TRUE

Use the relaxed CIS density in analysis.


RECOMMENDATION:

None


CIS_S2_THRESH

Determines whether a state is a singlet or triplet in unrestricted calculations.


TYPE:

INTEGER


DEFAULT:

120


OPTIONS:

$n$

Sets the $\langle \Hat {S}^2\rangle $ threshold to $n/100$


RECOMMENDATION:

For the default case, states with $\langle \Hat {S}^2\rangle > 1.2$ are treated as triplet states and other states are treated as singlets.


CIS_SINGLETS

Solve for singlet excited states (ignored for spin unrestricted systems)


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Solve for singlet states

FALSE

Do not solve for singlet states.


RECOMMENDATION:

None


CIS_STATE_DERIV

Sets CIS state for excited state optimizations and vibrational analysis.


TYPE:

INTEGER


DEFAULT:

0

Does not select any of the excited states.


OPTIONS:

$n$

Select the $n$th state.


RECOMMENDATION:

Check to see that the states do not change order during an optimization, due to state crossings.


CIS_TRIPLETS

Solve for triplet excited states (ignored for spin unrestricted systems)


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Solve for triplet states

FALSE

Do not solve for triplet states.


RECOMMENDATION:

None


CM5

Controls running of CM5 population analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculate CM5 populations.

FALSE

Do not calculate CM5 populations.


RECOMMENDATION:

None


COMBINE_K

Controls separate or combined builds for short-range and long-range K


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Build short-range and long-range K separately (twice as expensive as a global hybrid)

TRUE (or 1)

Build short-range and long-range K together ($\approx $ as expensive as a global hybrid)


RECOMMENDATION:

Most pre-defined range-separated hybrid functionals in Q-Chem use this feature by default. However, if a user-specified RSH is desired, it is necessary to manually turn this feature on.


COMPLEX_CCMAN

Requests complex-scaled or CAP-augmented CC/EOM calculations.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Engage complex CC/EOM code.


RECOMMENDATION:

Not available in CCMAN. Need to specify CAP strength or complex-scaling parameter in $complex_ccman section.


COMPLEX_MIX

Mix a certain percentage of the real part of the HOMO to the imaginary part of the LUMO.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0–100

The mix angle = $\pi \cdot $COMPLEX_MIX/100.


RECOMMENDATION:

It may help find the stable complex solution (similar idea as SCF_GUESS_MIX).


COMPLEX

Run an SCF calculation with complex MOs using GEN_SCFMAN.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Use complex orbitals.

FALSE

Use real orbitals.


RECOMMENDATION:

Set to TRUE if desired.


CORE_CHARACTER

Selects how the core orbitals are determined in the frozen-core approximation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use energy-based definition.

1-4

Use Mulliken-based definition (see Table 6.2 for details).


RECOMMENDATION:

Use the default, unless performing calculations on molecules with heavy elements.


CORE_IONIZE

Indicates how orbitals are specified for reduced excitation spaces.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

1

all valence orbitals are listed in $solute section

2

only hole(s) are specified all other occupations same as ground state


RECOMMENDATION:

For MOM + TDDFT this specifies the input form of the $solute section. If set to 1 all occupied orbitals must be specified, 2 only the empty orbitals to ignore must be specified.


CORRELATION

Specifies the correlation level of theory handled by CCMAN/CCMAN2.


TYPE:

STRING


DEFAULT:

None

No Correlation


OPTIONS:

CCMP2

Regular MP2 handled by CCMAN/CCMAN2

MP3

CCMAN and CCMAN2

MP4SDQ

CCMAN

MP4

CCMAN

CCD

CCMAN and CCMAN2

CCD(2)

CCMAN

CCSD

CCMAN and CCMAN2

CCSD(T)

CCMAN and CCMAN2

CCSD(2)

CCMAN

CCSD(fT)

CCMAN and CCMAN2

CCSD(dT)

CCMAN

CCVB-SD

CCMAN2

QCISD

CCMAN and CCMAN2

QCISD(T)

CCMAN and CCMAN2

OD

CCMAN

OD(T)

CCMAN

OD(2)

CCMAN

VOD

CCMAN

VOD(2)

CCMAN

QCCD

CCMAN

QCCD(T)

CCMAN

QCCD(2)

CCMAN

VQCCD

CCMAN

VQCCD(T)

CCMAN

VQCCD(2)

CCMAN


RECOMMENDATION:

Consult the literature for guidance.


CPSCF_NSEG

Controls the number of segments used to calculate the CPSCF equations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not solve the CPSCF equations in segments.

$n$

User-defined. Use $n$ segments when solving the CPSCF equations.


RECOMMENDATION:

Use the default.


CUBEFILE_STATE

Determines which excited state is used to generate cube files


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

Generate cube files for the $n$th excited state


RECOMMENDATION:

None


CUDA_RI-MP2

Enables GPU implementation of RI-MP2


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

GPU-enabled MGEMM off

TRUE

GPU-enabled MGEMM on


RECOMMENDATION:

Necessary to set to 1 in order to run GPU-enabled RI-MP2


CUTOCC

Specifies occupied orbital cutoff.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

0-200

CUTOFF = CUTOCC/100


RECOMMENDATION:

None


CUTVIR

Specifies virtual orbital cutoff.


TYPE:

INTEGER


DEFAULT:

0

No truncation


OPTIONS:

0-100

CUTOFF = CUTVIR/100


RECOMMENDATION:

None


DEUTERATE

Requests that all hydrogen atoms be replaces with deuterium.


TYPE:

LOGICAL


DEFAULT:

FALSE

Do not replace hydrogens.


OPTIONS:

TRUE

Replace hydrogens with deuterium.


RECOMMENDATION:

Replacing hydrogen atoms reduces the fastest vibrational frequencies by a factor of 1.4, which allow for a larger fictitious mass and time step in ELMD calculations. There is no reason to replace hydrogens in BOMD calculations.


DFPT_EXCHANGE

Specifies the secondary functional in a HFPC/DFPC calculation.


TYPE:

STRING


DEFAULT:

None


OPTIONS:

None


RECOMMENDATION:

See reference for recommended basis set, functional, and grid pairings.


DFPT_XC_GRID

Specifies the secondary grid in a HFPC/DFPC calculation.


TYPE:

STRING


DEFAULT:

None


OPTIONS:

None


RECOMMENDATION:

See reference for recommended basis set, functional, and grid pairings.


DFTVDW_ALPHA1

Parameter in XDM calculation with higher-order terms


TYPE:

INTEGER


DEFAULT:

83


OPTIONS:

10-1000


RECOMMENDATION:

None


DFTVDW_ALPHA2

Parameter in XDM calculation with higher-order terms.


TYPE:

INTEGER


DEFAULT:

155


OPTIONS:

10-1000


RECOMMENDATION:

None


DFTVDW_JOBNUMBER

Basic vdW job control


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not apply the XDM scheme.

1

Add vdW as energy/gradient correction to SCF.

2

Add vDW as a DFT functional and do full SCF (this option only works with XDM6).


RECOMMENDATION:

None


DFTVDW_KAI

Damping factor $k$ for $C_6$-only damping function


TYPE:

INTEGER


DEFAULT:

800


OPTIONS:

10–1000


RECOMMENDATION:

None


DFTVDW_METHOD

Choose the damping function used in XDM


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

1

Use Becke’s damping function including $C_6$ term only.

2

Use Becke’s damping function with higher-order ($C_8$ and $C_{10}$) terms.


RECOMMENDATION:

None


DFTVDW_MOL1NATOMS

The number of atoms in the first monomer in dimer calculation


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0–$N_{\rm atoms}$


RECOMMENDATION:

None


DFTVDW_PRINT

Printing control for VDW code


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

0

No printing.

1

Minimum printing (default)

2

Debug printing


RECOMMENDATION:

None


DFTVDW_USE_ELE_DRV

Specify whether to add the gradient correction to the XDM energy. only valid with Becke’s $C_6$ damping function using the interpolated BR89 model.


TYPE:

LOGICAL


DEFAULT:

1


OPTIONS:

1

Use density correction when applicable.

0

Do not use this correction (for debugging purposes).


RECOMMENDATION:

None


DFT_C

Controls whether the DFT-C empirical BSSE correction should be added.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

(or 0) Do not apply the DFT-C correction

TRUE

(or 1) Apply the DFT-C correction


RECOMMENDATION:

NONE


DFT_D3_3BODY

Controls whether the three-body interaction in Grimme’s DFT-D3 method should be applied (see Eq. (14) in Ref. Grimme:2010).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Do not apply the three-body interaction term

TRUE

Apply the three-body interaction term


RECOMMENDATION:

NONE


DFT_D3_A1

The nonlinear parameter $\alpha ^{}_1$ in Eqs. eq:bj-damping, eq:cso-damping, eq:zero-m-damping, and eq:op-damping. Used in DFT-D3(BJ), DFT-D3(CSO), DFT-D3M(0), DFT-D3M(BJ), and DFT-D3(op).


TYPE:

INTEGER


DEFAULT:

100000


OPTIONS:

$n$

Corresponding to $\alpha ^{}_1 = n/100000$.


RECOMMENDATION:

NONE


DFT_D3_A2

The nonlinear parameter $\alpha ^{}_2$ in Eqs. eq:bj-damping and eq:op-damping. Used in DFT-D3(BJ), DFT-D3M(BJ), and DFT-D3(op).


TYPE:

INTEGER


DEFAULT:

100000


OPTIONS:

$n$

Corresponding to $\alpha ^{}_2 = n/100000$.


RECOMMENDATION:

NONE


DFT_D3_POWER

The nonlinear parameter $\beta _6$ in Eq. eq:op-damping. Used in DFT-D3(op). Must be greater than or equal to 6 to avoid divergence.


TYPE:

INTEGER


DEFAULT:

600000


OPTIONS:

$n$

Corresponding to $\beta _6 = n/100000$.


RECOMMENDATION:

NONE


DFT_D3_RS6

The nonlinear parameter $s_{r,6}$ in Eqs. eq:zero-damping and Eq. eq:zero-m-damping. Used in DFT-D3(0) and DFT-D3M(0).


TYPE:

INTEGER


DEFAULT:

100000


OPTIONS:

$n$

Corresponding to $s_{r,6} = n/100000$.


RECOMMENDATION:

NONE


DFT_D3_RS8

The nonlinear parameter $s_{r,8}$ in Eqs. eq:zero-damping and Eq. eq:zero-m-damping. Used in DFT-D3(0) and DFT-D3M(0).


TYPE:

INTEGER


DEFAULT:

100000


OPTIONS:

$n$

Corresponding to $s_{r,8} = n/100000$.


RECOMMENDATION:

NONE


DFT_D3_S6

The linear parameter $s_6$ in eq. (5.32). Used in all forms of DFT-D3.


TYPE:

INTEGER


DEFAULT:

100000


OPTIONS:

$n$

Corresponding to $s_6 = n/100000$.


RECOMMENDATION:

NONE


DFT_D3_S8

The linear parameter $s_8$ in Eq. eq:D3eqn. Used in DFT-D3(0), DFT-D3(BJ), DFT-D3M(0), DFT-D3M(BJ), and DFT-D3(op).


TYPE:

INTEGER


DEFAULT:

100000


OPTIONS:

$n$

Corresponding to $s_8 = n/100000$.


RECOMMENDATION:

NONE


DFT_D_A

Controls the strength of dispersion corrections in the Chai–Head-Gordon DFT-D scheme, Eq. eqn:CHG.


TYPE:

INTEGER


DEFAULT:

600


OPTIONS:

$n$

Corresponding to $a = n/100$.


RECOMMENDATION:

Use the default.


DFT_D

Controls the empirical dispersion correction to be added to a DFT calculation.


TYPE:

LOGICAL


DEFAULT:

None


OPTIONS:

FALSE

(or 0) Do not apply the DFT-D2, DFT-CHG, or DFT-D3 scheme

EMPIRICAL_GRIMME

DFT-D2 dispersion correction from Grimme[Grimme(2006b)]

EMPIRICAL_CHG

DFT-CHG dispersion correction from Chai and Head-Gordon[Chai and Head-Gordon(2008b)]

EMPIRICAL_GRIMME3

DFT-D3(0) dispersion correction from Grimme (deprecated as

 

of Q-Chem 5.0)

D3_ZERO

DFT-D3(0) dispersion correction from Grimme et al.[Grimme et al.(2010)Grimme, Antony, Ehrlich, and Krieg]

D3_BJ

DFT-D3(BJ) dispersion correction from Grimme et al.[Grimme et al.(2011)Grimme, Ehrlich, and Goerigk]

D3_CSO

DFT-D3(CSO) dispersion correction from Schröder et al.[Schröder et al.(2015)Schröder, Creon, and Schwabe]

D3_ZEROM

DFT-D3M(0) dispersion correction from Smith et al.[Smith et al.(2016)Smith, Burns, Patkowski, and Sherrill]

D3_BJM

DFT-D3M(BJ) dispersion correction from Smith et al.[Smith et al.(2016)Smith, Burns, Patkowski, and Sherrill]

D3_OP

DFT-D3(op) dispersion correction from Witte et al.[Witte et al.(2017a)Witte, Mardirossian, Neaton, and Head-Gordon]

D3

Automatically select the "best" available D3 dispersion correction


RECOMMENDATION:

Use the D3 option, which selects the empirical potential based on the density functional specified by the user.


DH

Controls the application of DH-DFT scheme.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Do not apply the DH-DFT scheme

TRUE (or 1)

Apply DH-DFT scheme


RECOMMENDATION:

NONE


DIIS_ERR_RMS

Changes the DIIS convergence metric from the maximum to the RMS error.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE, FALSE


RECOMMENDATION:

Use the default, the maximum error provides a more reliable criterion.


DIIS_PRINT

Controls the output from DIIS SCF optimization.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Minimal print out.

1

Chosen method and DIIS coefficients and solutions.

2

Level 1 plus changes in multipole moments.

3

Level 2 plus Multipole moments.

4

Level 3 plus extrapolated Fock matrices.


RECOMMENDATION:

Use the default


DIIS_SEPARATE_ERRVEC

Control optimization of DIIS error vector in unrestricted calculations.


TYPE:

LOGICAL


DEFAULT:

FALSE

Use a combined $\alpha $ and $\beta $ error vector.


OPTIONS:

FALSE

Use a combined $\alpha $ and $\beta $ error vector.

TRUE

Use separate error vectors for the $\alpha $ and $\beta $ spaces.


RECOMMENDATION:

When using DIIS in Q-Chem a convenient optimization for unrestricted calculations is to sum the $\alpha $ and $\beta $ error vectors into a single vector which is used for extrapolation. This is often extremely effective, but in some pathological systems with symmetry breaking, can lead to false solutions being detected, where the $\alpha $ and $\beta $ components of the error vector cancel exactly giving a zero DIIS error. While an extremely uncommon occurrence, if it is suspected, set DIIS_SEPARATE_ERRVEC = TRUE to check.


DIIS_SUBSPACE_SIZE

Controls the size of the DIIS and/or RCA subspace during the SCF.


TYPE:

INTEGER


DEFAULT:

15


OPTIONS:

User-defined


RECOMMENDATION:

None


DIP_SINGLETS

Sets the number of singlet DIP roots to find. Valid only for closed-shell references.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any singlet DIP states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ DIP singlet states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


DIP_STATES

Sets the number of DIP roots to find. For closed-shell reference, defaults into DIP_SINGLETS. For open-shell references, specifies all low-lying states.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any DIP states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ DIP states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


DIP_TRIPLETS

Sets the number of triplet DIP roots to find. Valid only for closed-shell references.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any DIP triplet states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ DIP triplet states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


DIRECT_SCF

Controls direct SCF.


TYPE:

LOGICAL


DEFAULT:

Determined by program.


OPTIONS:

TRUE

Forces direct SCF.

FALSE

Do not use direct SCF.


RECOMMENDATION:

Use the default; direct SCF switches off in-core integrals.


DISP_FREE_C

Specify the employed “dispersion-free" correlation functional.


TYPE:

STRING


DEFAULT:

NONE


OPTIONS:

Correlation functionals supported by Q-Chem.


RECOMMENDATION:

Put the appropriate correlation functional paired with the chosen exchange functional (e.g. put PBE if DISP_FREE_X is revPBE); put NONE if DISP_FREE_X is set to an exchange-correlation functional.


DISP_FREE_X

Specify the employed “dispersion-free" exchange functional.


TYPE:

STRING


DEFAULT:

HF


OPTIONS:

Exchange functionals (e.g. revPBE) or exchange-correlation functionals (e.g. B3LYP)

supported by Q-Chem.


RECOMMENDATION:

HF is recommended for hybrid (primary) functionals (e.g.$\omega $B97X-V) and revPBE for semi-local ones (e.g.B97M-V). Other reasonable options (e.g. B3LYP for B3LYP-D3) can also be applied.


DORAMAN

Controls calculation of Raman intensities. Requires JOBTYPE to be set to FREQ


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not calculate Raman intensities.

TRUE

Do calculate Raman intensities.


RECOMMENDATION:

None


DSF_STATES

Sets the number of doubly spin-flipped target states roots to find.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any DSF states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ doubly spin-flipped states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


DUAL_BASIS_ENERGY

Activates dual-basis SCF (HF or DFT) energy correction.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

Analytic first derivative available for HF and DFT (see JOBTYPE)

Can be used in conjunction with MP2 or RI-MP2

See BASIS, BASIS2, BASISPROJTYPE


RECOMMENDATION:

Use dual-basis to capture large-basis effects at smaller basis cost. Particularly useful with RI-MP2, in which HF often dominates. Use only proper subsets for small-basis calculation.


D_CPSCF_PERTNUM

Specifies whether to do the perturbations one at a time, or all together.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Perturbed densities to be calculated all together.

1

Perturbed densities to be calculated one at a time.


RECOMMENDATION:

None


D_SCF_CONV_1

Sets the convergence criterion for the level-1 iterations. This preconditions the density for the level-2 calculation, and does not include any two-electron integrals.


TYPE:

INTEGER


DEFAULT:

corresponding to a threshold of $10^{-4}$.


OPTIONS:

$n<10$

Sets convergence threshold to $10^{-n}$.


RECOMMENDATION:

The criterion for level-1 convergence must be less than or equal to the level-2 criterion, otherwise the D-CPSCF will not converge.


D_SCF_CONV_2

Sets the convergence criterion for the level-2 iterations.


TYPE:

INTEGER


DEFAULT:

4

Corresponding to a threshold of $10^{-4}$.


OPTIONS:

$n<10$

Sets convergence threshold to $10^{-n}$.


RECOMMENDATION:

None


D_SCF_DIIS

Specifies the number of matrices to use in the DIIS extrapolation in the D-CPSCF.


TYPE:

INTEGER


DEFAULT:

11


OPTIONS:

$n$

$n$ = 0 specifies no DIIS extrapolation is to be used.


RECOMMENDATION:

Use the default.


D_SCF_MAX_1

Sets the maximum number of level-1 iterations.


TYPE:

INTEGER


DEFAULT:

100


OPTIONS:

$n$

User defined.


RECOMMENDATION:

Use the default.


D_SCF_MAX_2

Sets the maximum number of level-2 iterations.


TYPE:

INTEGER


DEFAULT:

30


OPTIONS:

$n$ User defined.


RECOMMENDATION:

Use the default.


EA_STATES

Sets the number of attached target states roots to find. By default, $\alpha $ electron will be attached (see EOM_EA_ALPHA).


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any EA states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ EA states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


ECP

Defines the effective core potential and associated basis set to be used


TYPE:

STRING


DEFAULT:

No ECP


OPTIONS:

General, Gen

User defined. ($ecp keyword required)

Symbol

Use standard ECPs discussed above.


RECOMMENDATION:

ECPs are recommended for first row transition metals and heavier elements. Consul the reviews for more details.


EDA2

Switch on EDA2 and specify the option set number.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not run through EDA2.

1

Frozen energy decomposition + nDQ-FERF polarization

 

(the standard EDA2 option)

2

Frozen energy decomposition + (AO-block-based) ALMO polarization

 

(old scheme with the addition of frozen decomposition)

3

Frozen energy decomposition + oDQ-FERF polarization

 

(NOT commonly used)

4

Frozen wave function relaxation + Frozen energy decomposition + nDQ-FERF polarization

 

(NOT commonly used)

5

Frozen energy decomposition + polMO polarization

 

(NOT commonly used).

10

No preset. Completely controlled by user’s $rem input

 

(for developers only)


RECOMMENDATION:

Turn on EDA2 for Q-Chem’s ALMO-EDA jobs unless CTA with the old scheme is desired. Option 1 is recommended in general, especially when substantially large basis sets are employed. The original ALMO scheme (option 2) can be used when the employed basis set is of small or medium size (arguably no larger than augmented triple-$\zeta $). The other options are rarely used for routine applications.


EDA_BSSE

Calculates the BSSE correction when performing the energy decomposition analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Set to TRUE unless a very large basis set is used.


EDA_CLS_DISP

Compute the DISP contribution without performing the orthogonal decomposition, which will then be subtracted from the classical PAULI term.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Use the DISP term computed with orthogonal decomposition (if available).

TRUE

Use the DISP term computed using undistorted monomer densities.


RECOMMENDATION:

Set it to TRUE when orthogonal decomposition is not performed.


EDA_CLS_ELEC

Perform the classical decomposition of the frozen term.


TYPE:

BOOLEAN


DEFAULT:

FALSE (automatically set to TRUE by EDA2 options 1–5)


OPTIONS:

FALSE

Do not compute the classical ELEC and PAULI terms.

TRUE

Perform the classical decomposition.


RECOMMENDATION:

TRUE


EDA_COVP

Perform COVP analysis when evaluating the RS or ARS charge-transfer correction. COVP analysis is currently implemented only for systems of two fragments.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Set to TRUE to perform COVP analysis in an EDA or SCF MI(RS) job.


EDA_PRINT_COVP

Replace the final MOs with the CVOP orbitals in the end of the run.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Set to TRUE to print COVP orbitals instead of conventional MOs.


EE_SINGLETS

Controls the number of singlet excited states to calculate.


TYPE:

INTEGER/ARRAY


DEFAULT:

0

Do not perform an ADC calculation of singlet excited states


OPTIONS:

$n>0$

Number of singlet states to calculate for each irrep or

$[n_1, n_2, ...]$

Compute $n_1$ states for the first irrep, $n_2$ states for the second irrep, ...


RECOMMENDATION:

Use this variable to define the number of excited states in case of restricted calculations of singlet states. In unrestricted calculations it can also be used, if EE_STATES not set. Then, it has the same effect as setting EE_STATES.


EE_STATES

Controls the number of excited states to calculate.


TYPE:

INTEGER/ARRAY


DEFAULT:

0

Do not perform an ADC calculation


OPTIONS:

$n>0$

Number of states to calculate for each irrep or

$[n_1, n_2, ...]$

Compute $n_1$ states for the first irrep, $n_2$ states for the second irrep, ...


RECOMMENDATION:

Use this variable to define the number of excited states in case of unrestricted or open-shell calculations. In restricted calculations it can also be used, if neither EE_SINGLETS nor EE_TRIPLETS is given. Then, it has the same effect as setting EE_SINGLETS.


EE_TRIPLETS

Controls the number of triplet excited states to calculate.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not perform an ADC calculation of triplet excited states


OPTIONS:

$n>0$

Number of triplet states to calculate for each irrep or

$[n_1, n_2, ...]$

Compute $n_1$ states for the first irrep, $n_2$ states for the second irrep, ...


RECOMMENDATION:

Use this variable to define the number of excited states in case of restricted calculations of triplet states.


EFP_COORD_XYZ

Use coordinates of three atoms instead of Euler angles to specify position and orientation of the fragments


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE FALSE


RECOMMENDATION:

None


EFP_DIRECT_POLARIZATION_DRIVER

Use direct solver for EFP polarization


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE FALSE


RECOMMENDATION:

Direct polarization solver provides stable convergence of induced dipoles which may otherwise become problematic in case of closely lying or highly polar or charged fragments. The computational cost of direct polarization versus iterative polarization becomes higher for systems containing more than  10000 polarizable points.


EFP_DISP_DAMP

Controls fragment-fragment dispersion screening in EFP


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

0

switch off dispersion screening

1

use Tang-Toennies screening, with fixed parameter $b=1.5$

2

use overlap-based damping


RECOMMENDATION:

None


EFP_DISP

Controls fragment-fragment dispersion in EFP


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

switch on dispersion

FALSE

switch off dispersion


RECOMMENDATION:

None


EFP_ELEC_DAMP

Controls fragment-fragment electrostatic screening in EFP


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

0

switch off electrostatic screening

1

use overlap-based damping correction

2

use exponential damping correction if screening parameters are provided in the EFP potential


RECOMMENDATION:

Overlap-based damping is recommended


EFP_ELEC

Controls fragment-fragment electrostatics in EFP


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

switch on electrostatics

FALSE

switch off electrostatics


RECOMMENDATION:

None


EFP_ENABLE_LINKS

Enable fragment links in EFP region


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE FALSE


RECOMMENDATION:

None


EFP_EXREP

Controls fragment-fragment exchange repulsion in EFP


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

switch on exchange repulsion

FALSE

switch off exchange repulsion


RECOMMENDATION:

None


EFP_FRAGMENTS_ONLY

Specifies whether there is a QM part


TYPE:

LOGICAL


DEFAULT:

FALSE

QM part is present


OPTIONS:

TRUE

Only MM part is present: all fragments are treated by EFP

FALSE

QM part is present: do QM/MM EFP calculation


RECOMMENDATION:

None


EFP_INPUT

Specifies the format of EFP input


TYPE:

LOGICAL


DEFAULT:

FALSE

Dummy atom (e.g., He) in $molecule section should be present


OPTIONS:

TRUE

A format without dummy atom in $molecule section

FALSE

A format with dummy atom in $molecule section


RECOMMENDATION:

None


EFP_POL_DAMP

Controls fragment-fragment polarization screening in EFP


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

0

switch off polarization screening

1

use Tang-Toennies screening


RECOMMENDATION:

None


EFP_POL

Controls fragment-fragment polarization in EFP


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

switch on polarization

FALSE

switch off polarization


RECOMMENDATION:

None


EFP_QM_DISP

Controls QM-EFP dispersion


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

switch on QM-EFP dispersion

FALSE

switch off QM-EFP dispersion


RECOMMENDATION:

None


EFP_QM_ELEC_DAMP

Controls QM-EFP electrostatics screening in EFP


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

switch off electrostatic screening

1

use overlap based damping correction


RECOMMENDATION:

None


EFP_QM_ELEC

Controls QM-EFP electrostatics


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

switch on QM-EFP electrostatics

FALSE

switch off QM-EFP electrostatics


RECOMMENDATION:

None


EFP_QM_EXREP

Controls QM-EFP exchange-repulsion


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

switch on QM-EFP exchange-repulsion

FALSE

switch off QM-EFP exchange-repulsion


RECOMMENDATION:

None


EFP_QM_POL

Controls QM-EFP polarization


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

switch on QM-EFP polarization

FALSE

switch off QM-EFP polarization


RECOMMENDATION:

None


EFP

Specifies that EFP calculation is requested


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE FALSE


RECOMMENDATION:

The keyword should be present if excited state calculation is requested


EMBEDMAN

Turns density embedding on.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not use density embedding.

1

Turn on density embedding.


RECOMMENDATION:

Use EMBEDMAN for QM/QM density embedded calculations.


EMBED_MU

Specifies exponent value of projection operator scaling factor, $\mu $ [Eq. eq:des_fock and eq:des_corr].


TYPE:

INTEGER


DEFAULT:

7


OPTIONS:

n

$\mu = 10^{n}$.


RECOMMENDATION:

Values of 2 - 7 are recommended. A higher value of $\mu $ leads to better orthogonality of the fragment MOs but $\mu > 10^{7}$ introduces numerical noise. $\mu < 10^{2}$ results in non-additive terms becoming too large. Energy corrections are fairly insensitive to changes in $\mu $ within the range of $10^{2} - 10^{7}$.


EMBED_THEORY

Specifies post-DFT method performed on fragment one.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

No post HF method, only DFT on fragment one.

1

Perform CCSD(T) calculation on fragment one.

2

Perform MP2 calculation on fragment one.


RECOMMENDATION:

This should be 1 or 2 for the high-level QM calculation of fragment 1-in-2, and 0 for fragment 2-in-1 low-level QM calculation.


EMBED_THRESH

Specifies threshold cutoff for AO contribution used to determine which MOs belong to which fragments


TYPE:

INTEGER


DEFAULT:

500


OPTIONS:

n

Threshold $ = n/1000$


RECOMMENDATION:

Acceptable values range from 0 to 1000. Should only need to be tuned for non-highly localized MOs


EOM_CORR

Specifies the correlation level.


TYPE:

STRING


DEFAULT:

None

No correction will be computed


OPTIONS:

SD(DT)

EOM-CCSD(dT), available for EE, SF, and IP

SD(FT)

EOM-CCSD(fT), available for EE, SF, IP, and EA

SD(ST)

EOM-CCSD(sT), available for IP


RECOMMENDATION:

None


EOM_DAVIDSON_CONVERGENCE

Convergence criterion for the RMS residuals of excited state vectors.


TYPE:

INTEGER


DEFAULT:

5

Corresponding to $10^{-5}$


OPTIONS:

$n$

Corresponding to $10^{-n}$ convergence criterion


RECOMMENDATION:

Use the default. Normally this value be the same as EOM_DAVIDSON_THRESHOLD.


EOM_DAVIDSON_MAXVECTORS

Specifies maximum number of vectors in the subspace for the Davidson diagonalization.


TYPE:

INTEGER


DEFAULT:

60


OPTIONS:

$n$

Up to $n$ vectors per root before the subspace is reset


RECOMMENDATION:

Larger values increase disk storage but accelerate and stabilize convergence.


EOM_DAVIDSON_MAX_ITER

Maximum number of iteration allowed for Davidson diagonalization procedure.


TYPE:

INTEGER


DEFAULT:

30


OPTIONS:

$n$

User-defined number of iterations


RECOMMENDATION:

Default is usually sufficient


EOM_DAVIDSON_THRESHOLD

Specifies threshold for including a new expansion vector in the iterative Davidson diagonalization. Their norm must be above this threshold.


TYPE:

INTEGER


DEFAULT:

00103

Corresponding to 0.00001


OPTIONS:

$abcde$

Integer code is mapped to $abc\times 10^{-(de+2)}$, i.e., 02505->2.5$\times 10^{-6}$


RECOMMENDATION:

Use the default unless converge problems are encountered. Should normally be set to the same values as EOM_DAVIDSON_CONVERGENCE, if convergence problems arise try setting to a value slightly larger than EOM_DAVIDSON_CONVERGENCE.


EOM_EA_ALPHA

Sets the number of attached target states derived by attaching $\alpha $ electron (M$_ s$=${{1}\over {2}}$, default in EOM-EA).


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any EA states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ EA states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


EOM_EA_BETA

Sets the number of attached target states derived by attaching $\beta $ electron (M$_ s$=$-{{1}\over {2}}$, EA-SF).


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any EA states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ EA states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


EOM_FAKE_IPEA

If TRUE, calculates fake EOM-IP or EOM-EA energies and properties using the diffuse orbital trick. Default for EOM-EA and Dyson orbital calculations in CCMAN.


TYPE:

LOGICAL


DEFAULT:

FALSE (use proper EOM-IP code)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

None. This feature only works for CCMAN.


EOM_IPEA_FILTER

If TRUE, filters the EOM-IP/EA amplitudes obtained using the diffuse orbital implementation (see EOM_FAKE_IPEA). Helps with convergence.


TYPE:

LOGICAL


DEFAULT:

FALSE (EOM-IP or EOM-EA amplitudes will not be filtered)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

None


EOM_IP_ALPHA

Sets the number of ionized target states derived by removing $\alpha $ electron (M$_ s=-{{1}\over {2}}$).


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any IP/$\alpha $ states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ ionized states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


EOM_IP_BETA

Sets the number of ionized target states derived by removing $\beta $ electron (M$_ s$=${{1}\over {2}}$, default for EOM-IP).


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any IP/$\beta $ states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ ionized states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


EOM_NGUESS_DOUBLES

Specifies number of excited state guess vectors which are double excitations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Include $n$ guess vectors that are double excitations


RECOMMENDATION:

This should be set to the expected number of doubly excited states, otherwise they may not be found.


EOM_NGUESS_SINGLES

Specifies number of excited state guess vectors that are single excitations.


TYPE:

INTEGER


DEFAULT:

Equal to the number of excited states requested


OPTIONS:

$n$

Include $n$ guess vectors that are single excitations


RECOMMENDATION:

Should be greater or equal than the number of excited states requested, unless .


EOM_POL

Whether or not the static polarizability for the EOM-CCSD wave function will be calculated.


TYPE:

LOGICAL


DEFAULT:

FALSE (EOM polarizability will not be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

Static polarizabilities are expensive since they require solving three additional response equations. Do no request this property unless you need it.


EOM_PRECONV_DOUBLES

When not zero, doubly excited vectors are converged prior to a full excited states calculation. Sets the maximum number of iterations for pre-converging procedure


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not pre-converge

N

Perform N Davidson iterations pre-converging doubles.


RECOMMENDATION:

Occasionally necessary to ensure a doubly excited state is found. Also used in DSF calculations instead of EOM_PRECONV_SINGLES


EOM_PRECONV_SD

When not zero, EOM vectors are pre-converged prior to a full excited states calculation. Sets the maximum number of iterations for pre-converging procedure.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

do not pre-converge

N

perform N Davidson iterations pre-converging singles and doubles.


RECOMMENDATION:

Occasionally necessary to ensure that all low-lying states are found. Also, very useful in EOM(2,3) calculations.


None

EOM_PRECONV_SINGLES

When not zero, singly excited vectors are converged prior to a full excited states calculation. Sets the maximum number of iterations for pre-converging procedure.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

do not pre-converge

1

pre-converge singles


RECOMMENDATION:

Sometimes helps with problematic convergence.


EOM_REF_PROP_TE

Request for calculation of non-relaxed two-particle EOM-CC properties. The two-particle properties currently include $\ensuremath{\langle }S^2\ensuremath{\rangle }$. The one-particle properties also will be calculated, since the additional cost of the one-particle properties calculation is inferior compared to the cost of $\ensuremath{\langle }S^2\ensuremath{\rangle }$. The variable CC_EOM_PROP must be also set to TRUE. Alternatively, CC_CALC_SSQ can be used to request $\ensuremath{\langle }S^2\ensuremath{\rangle }$ calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE

(no two-particle properties will be calculated)


OPTIONS:

FALSE, TRUE


RECOMMENDATION:

The two-particle properties are computationally expensive since they require calculation and use of the two-particle density matrix (the cost is approximately the same as the cost of an analytic gradient calculation). Do not request the two-particle properties unless you really need them.


EOM_SHIFT

Specifies energy shift in EOM calculations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

corresponds to $n\cdot 10^{-3}$ hartree shift (i.e., 11000 = 11 hartree); solve for eigenstates around this value.


RECOMMENDATION:

Not available in CCMAN.


EOM_USER_GUESS

Specifies if user-defined guess will be used in EOM calculations.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Solve for a state that has maximum overlap with a trans-n specified in $eom_user_guess.


RECOMMENDATION:

The orbitals are ordered by energy, as printed in the beginning of the CCMAN2 output. Not available in CCMAN.


EPAO_ITERATE

Controls iterations for EPAO calculations (see PAO_METHOD).


TYPE:

INTEGER


DEFAULT:

0

Use non-iterated EPAOs based on atomic blocks of SPS.


OPTIONS:

$n$

Optimize the EPAOs for up to $n$ iterations.


RECOMMENDATION:

Use the default. For molecules that are not too large, one can test the sensitivity of the results to the type of minimal functions by the use of optimized EPAOs in which case a value of $n=500$ is reasonable.


EPAO_WEIGHTS

Controls algorithm and weights for EPAO calculations (see PAO_METHOD).


TYPE:

INTEGER


DEFAULT:

115

Standard weights, use 1$^{\ensuremath{\mathrm{st}}}$ and 2$^{\ensuremath{\mathrm{nd}}}$ order optimization


OPTIONS:

15 

Standard weights, with 1$^{\ensuremath{\mathrm{st}}}$ order optimization only.


RECOMMENDATION:

Use the default, unless convergence failure is encountered.


ERCALC

Specifies the Edmiston-Ruedenberg localized orbitals are to be calculated


TYPE:

INTEGER


DEFAULT:

06000


OPTIONS:

$aabcd$

 

$aa$

specifies the convergence threshold.

 

If $aa>3$, the threshold is set to $10^{-aa}$. The default is 6.

 

If $aa=1$, the calculation is aborted after the guess, allowing Pipek-Mezey

 

orbitals to be extracted.

$b$

specifies the guess:

 

0 Boys localized orbitals. This is the default

 

1 Pipek-Mezey localized orbitals.

$c$

specifies restart options (if restarting from an ER calculation):

 

0 No restart. This is the default

 

1 Read in MOs from last ER calculation.

 

2 Read in MOs and RI integrals from last ER calculation.

$d$

specifies how to treat core orbitals

 

0 Do not perform ER localization. This is the default.

 

1 Localize core and valence together.

 

2 Do separate localizations on core and valence.

 

3 Localize only the valence electrons.

 

4 Use the $localize section.


RECOMMENDATION:

ERCALC 1 will usually suffice, which uses threshold $10^{-6}$.


ER_CIS_NUMSTATE

Define how many states to mix with ER localized diabatization. These states must be specified in the $localized_diabatization section.


TYPE:

INTEGER


DEFAULT:

0

Do not perform ER localized diabatization.


OPTIONS:

2 to N where N is the number of CIS states requested (CIS_N_ROOTS)


RECOMMENDATION:

It is usually not wise to mix adiabatic states that are separated by more than a few eV or a typical reorganization energy in solvent.


ESP_TRANS

Controls the calculation of the electrostatic potential of the transition density


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

compute the electrostatic potential of the excited state transition density

FALSE

compute the electrostatic potential of the excited state electronic density


RECOMMENDATION:

NONE


EXCHANGE

Specifies the exchange functional (or most exchange-correlation functionals for backwards compatibility).


TYPE:

STRING


DEFAULT:

No default


OPTIONS:

NAME

Use EXCHANGE = NAME, where NAME is either:

 

1) One of the exchange functionals listed in Section 5.3.2

 

2) One of the XC functionals listed in Section 5.3.4 that is not marked with an

 

asterisk.

 

3) GEN, for a user-defined functional (see Section 5.3.6).


RECOMMENDATION:

In general, consult the literature to guide your selection. Our recommendations are indicated in bold in Sections 5.3.4 and  5.3.2.


FAST_XC

Controls direct variable thresholds to accelerate exchange-correlation (XC) in DFT.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Turn FAST_XC on.

FALSE

Do not use FAST_XC.


RECOMMENDATION:

Caution: FAST_XC improves the speed of a DFT calculation, but may occasionally cause the SCF calculation to diverge.


FDE

Turns density embedding on.


TYPE:

BOOLEAN


DEFAULT:

False


OPTIONS:

True

Perform an FDE-ADC calculation.

False

Don’t perform FDE-ADC calculation.


RECOMMENDATION:

Set the $rem variable FDE to TRUE to start a FDE-ADC calculation.


FDIFF_DER

Controls what types of information are used to compute higher derivatives. The default uses a combination of energy, gradient and Hessian information, which makes the force field calculation faster.


TYPE:

INTEGER


DEFAULT:

3

for jobs where analytical 2nd derivatives are available.

0

for jobs with ECP.


OPTIONS:

0

Use energy information only.

1

Use gradient information only.

2

Use Hessian information only.

3

Use energy, gradient, and Hessian information.


RECOMMENDATION:

When the molecule is larger than benzene with small basis set, FDIFF_DER=2 may be faster. Note that FDIFF_DER will be set lower if analytic derivatives of the requested order are not available. Please refers to IDERIV.


FDIFF_STEPSIZE_QFF

Displacement used for calculating third and fourth derivatives by finite difference.


TYPE:

INTEGER


DEFAULT:

5291

Corresponding to 0.1 bohr. For calculating third and fourth derivatives.


OPTIONS:

$n$

Use a step size of $n\times 10^{-5}$.


RECOMMENDATION:

Use the default, unless the potential surface is very flat, in which case a larger value should be used.


FDIFF_STEPSIZE

Displacement used for calculating derivatives by finite difference.


TYPE:

INTEGER


DEFAULT:

100

Corresponding to 0.001 Å. For calculating second derivatives.


OPTIONS:

$n$

Use a step size of $n\times 10^{-5}$.


RECOMMENDATION:

Use the default except in cases where the potential surface is very flat, in which case a larger value should be used. See FDIFF_STEPSIZE_QFF for third and fourth derivatives.


FD_MAT_VEC_PROD

Compute Hessian-vector product using the finite difference technique.


TYPE:

BOOLEAN


DEFAULT:

FALSE (TRUE when the employed functional contains NLC)


OPTIONS:

FALSE

Compute Hessian-vector product analytically.

TRUE

Use finite difference to compute Hessian-vector product.


RECOMMENDATION:

Set it to TRUE when analytical Hessian is not available.

Note: 

For simple R and U calculations, it can always be set to FALSE, which indicates that

only the NLC part will be computed with finite difference.


FEFP_EFP

Specifies that fEFP_EFP calculation is requested to compute the total interaction energies between a ligand (the last fragment in the $efp_fragments section) and the protein (represented by fEFP)


TYPE:

STRING


DEFAULT:

OFF


OPTIONS:

OFF

disables fEFP

LA

enables fEFP with the Link Atom (HLA or CLA) scheme (only electrostatics and polarization)

MFCC

enables fEFP with MFCC (only electrostatics)


RECOMMENDATION:

The keyword should be invoked if EFP/fEFP is requested (interaction energy calculations). This keyword has to be employed with EFP_FRAGMENT_ONLY = TRUE. To switch on/off electrostatics or polarzation interactions, the usual EFP controls are employed.


FEFP_QM

Specifies that fEFP_QM calculation is requested to perform a QM/fEFPcompute computation. The fEFP part is a fractionated macromolecule.


TYPE:

STRING


DEFAULT:

OFF


OPTIONS:

OFF

disables fEFP_QM and performs a QM/EFP calculation

LA

enables fEFP_QM with the Link Atom scheme


RECOMMENDATION:

The keyword should be invoked if QM/fEFP is requested. This keyword has to be employed with efp_fragment_only false. Only electrostatics is available.


FMO_ORDER

Controls the truncation order $n$ for FMO.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$N$

Order of FMO


RECOMMENDATION:

FMO can be performed up to third order.


FOA_FUNDGAP

Compute the frozen-orbital approximation of the fundamental gap.


TYPE:

Boolean


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not compute FOA derivative discontinuity and fundamental gap.

TRUE

Compute and print FOA fundamental gap information. Implies KS_GAP_PRINT.


RECOMMENDATION:

Use in conjunction with KS_GAP_UNIT if true.


FOCK_EXTRAP_ORDER

Specifies the polynomial order $N$ for Fock matrix extrapolation.


TYPE:

INTEGER


DEFAULT:

0

Do not perform Fock matrix extrapolation.


OPTIONS:

$N$

Extrapolate using an $N$th-order polynomial ($N > 0$).


RECOMMENDATION:

None


FOCK_EXTRAP_POINTS

Specifies the number $M$ of old Fock matrices that are retained for use in extrapolation.


TYPE:

INTEGER


DEFAULT:

0

Do not perform Fock matrix extrapolation.


OPTIONS:

$M$

Save $M$ Fock matrices for use in extrapolation $(M > N)$


RECOMMENDATION:

Higher-order extrapolations with more saved Fock matrices are faster and conserve energy better than low-order extrapolations, up to a point. In many cases, the scheme ($N$ = 6, $M$ = 12), in conjunction with SCF_CONVERGENCE = 6, is found to provide about a 50% savings in computational cost while still conserving energy.


FOLLOW_ENERGY

Adjusts the energy window for near states


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use dynamic thresholds, based on energy difference between steps.

$n$

Search over selected state $E_{\rm est}\pm n\times 10^{-6}\;  E_ h$.


RECOMMENDATION:

Use a wider energy window to follow a state diabatically, smaller window to remain on the adiabatic state most of the time.


FOLLOW_OVERLAP

Adjusts the threshold for states of similar character.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use dynamic thresholds, based on energy difference between steps.

$n$

Percentage overlap for previous step and current step.


RECOMMENDATION:

Use a higher value to require states have higher degree of similarity to be considered the same (more often selected based on energy).


FON_E_THRESH

DIIS error below which occupations will be kept constant.


TYPE:

INTEGER


DEFAULT:

4


OPTIONS:

n

freeze occupations below DIIS error of $10^{-n}$


RECOMMENDATION:

This should be one or two numbers bigger than the desired SCF convergence threshold.


FON_NORB

Number of orbitals above and below the Fermi level that are allowed to have fractional occupancies.


TYPE:

INTEGER


DEFAULT:

4


OPTIONS:

n

number of active orbitals


RECOMMENDATION:

The number of valence orbitals is a reasonable choice.


FON_T_END

Final electronic temperature for FON calculation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

Any desired final temperature.


RECOMMENDATION:

Pick the temperature to either reproduce experimental conditions (e.g. room temperature) or as low as possible to approach zero-temperature.


FON_T_METHOD

Selects cooling algorithm.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

1

temperature is scaled by a factor in each cycle

2

temperature is decreased by a constant number in each cycle


RECOMMENDATION:

We have made slightly better experience with a constant cooling rate. However, choose constant temperature when in doubt.


FON_T_SCALE

Determines the step size for the cooling.


TYPE:

INTEGER


DEFAULT:

90


OPTIONS:

n

temperature is scaled by $0.01 \cdot n$ in each cycle (cooling method 1)

n

temperature is decreased by n K in each cycle (cooling method 2)


RECOMMENDATION:

The cooling rate should be neither too slow nor too fast. Too slow may lead to final energies that are at undesirably high temperatures. Too fast may lead to convergence issues. Reasonable choices for methods 1 and 2 are 98 and 50, respectively. When in doubt, use constant temperature.


FON_T_START

Initial electronic temperature (in K) for FON calculation.


TYPE:

INTEGER


DEFAULT:

1000


OPTIONS:

Any desired initial temperature.


RECOMMENDATION:

Pick the temperature to either reproduce experimental conditions (e.g. room temperature) or as low as possible to approach zero-temperature.


FORCE_FIELD

Specifies the force field for MM energies in QM/MM calculations.


TYPE:

STRING


DEFAULT:

NONE


OPTIONS:

AMBER99

AMBER99 force field

CHARMM27

CHARMM27 force field

OPLSAA

OPLSAA force field


RECOMMENDATION:

None.


FRACTIONAL_ELECTRON

Add or subtract a fraction of an electron.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use an integer number of electrons.

$n$

Add $n/1000$ electrons to the system.


RECOMMENDATION:

Use only if trying to generate $E(N)$ plots. If $n < 0$, a fraction of an electron is removed from the system.


FRAGMO_GUESS_MODE

Decide what to do regarding to the FRAGMO guess in the present job.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Spawn fragment jobs sequentially and collect the results as the FRAGMO guess at the end.

1

Generate fragment inputs in folders “FrgX" under the scratch directory of the present job

 

and then terminate. Users can then take advantage of a queuing system to run these jobs

 

simultaneously using “FrgX" as their scratch folders (should be handled with scripting).

2

Read in the available fragment data.


RECOMMENDATION:

Consider using “1" if the fragment calculations are evenly expensive. Use “2" when FRAGMO guess is pre-computed.


FRAG_MOL_ORB

Perform a FMO calculation.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform a FMO calculation.

FALSE

Do not perform a FMO calculation.


RECOMMENDATION:

NONE


FRGM_LPCORR

Specifies a correction method performed after the locally-projected equations are converged.


TYPE:

STRING


DEFAULT:

NONE


OPTIONS:

ARS

Approximate Roothaan-step perturbative correction.

RS

Single Roothaan-step perturbative correction.

EXACT_SCF

Full SCF variational correction.

ARS_EXACT_SCF

Both ARS and EXACT_SCF in a single job.

RS_EXACT_SCF

Both RS and EXACT_SCF in a single job.


RECOMMENDATION:

For large basis sets use ARS, use RS if ARS fails.


FRGM_METHOD

Specifies a locally-projected method.


TYPE:

STRING


DEFAULT:

NONE


OPTIONS:

STOLL

Locally-projected SCF equations of Stoll are solved.

GIA

Locally-projected SCF equations of Gianinetti are solved.

NOSCF_RS

Single Roothaan-step correction to the FRAGMO initial guess.

NOSCF_ARS

Approximate single Roothaan-step correction to the FRAGMO initial guess.

NOSCF_DRS

Double Roothaan-step correction to the FRAGMO initial guess.

NOSCF_RS_FOCK

Non-converged SCF energy of the single Roothaan-step MOs.


RECOMMENDATION:

STOLL and GIA are for variational optimization of the ALMOs. NOSCF options are for computationally fast corrections of the FRAGMO initial guess.


FRZ_GEOM

Compute forces on the frozen PES.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not compute forces on the frozen PES.

TRUE

Compute forces on the frozen PES.


RECOMMENDATION:

Set it to TRUE when optimized geometry or vibrational frequencies on the frozen PES are desired.


FRZ_ORTHO_DECOMP_CONV

Convergence criterion for the minimization problem that gives the orthogonal fragment densities.


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$n$

$10^{-n}$


RECOMMENDATION:

Use the default unless tighter convergence is preferred.


FRZ_ORTHO_DECOMP

Perform the decomposition of frozen interaction energy based on the orthogonal decomposition of the 1PDM associated with the frozen wave function.


TYPE:

BOOLEAN


DEFAULT:

FALSE (automatically set to TRUE by EDA2 options 1–5)


OPTIONS:

FALSE

Do not perform the orthogonal decomposition.

TRUE

Perform the frozen energy decomposition using orthogonal fragment densities.


RECOMMENDATION:

Use default value automatically set by “EDA2".


FSM_MODE

Specifies the method of interpolation


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

1

Cartesian

2

LST


RECOMMENDATION:

In most cases, LST is superior to Cartesian interpolation.


FSM_NGRAD

Specifies the number of perpendicular gradient steps used to optimize each node


TYPE:

INTEGER


DEFAULT:

Undefined


OPTIONS:

$N$

Number of perpendicular gradients per node


RECOMMENDATION:

Anything between 2 and 6 should work, where increasing the number is only needed for difficult reaction paths.


FSM_NNODE

Specifies the number of nodes along the string


TYPE:

INTEGER


DEFAULT:

Undefined


OPTIONS:

$N$

number of nodes in FSM calculation


RECOMMENDATION:

$N=15$. Use 10 to 20 nodes for a typical calculation. Reaction paths that connect multiple elementary steps should be separated into individual elementary steps, and one FSM job run for each pair of intermediates. Use a higher number when the FSM is followed by an approximate-Hessian based transition state search (Section 10.2.2).


FSM_OPT_MODE

Specifies the method of optimization


TYPE:

INTEGER


DEFAULT:

Undefined


OPTIONS:

1

Conjugate gradients

2

Quasi-Newton method with BFGS Hessian update


RECOMMENDATION:

The quasi-Newton method is more efficient when the number of nodes is high.


FSSH_CONTINUE

Restart a FSSH calculation from a previous run, using the file 396.0. When this is enabled, the initial conditions of the surface hopping calculation will be set, including the correct wave function amplitudes, initial surface, and position/momentum moments (if AFSSH) from the final step of some prior calculation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$0$

Start fresh calculation.

$1$

Restart from previous run.


RECOMMENDATION:

None


FSSH_INITIALSURFACE

Specifies the initial state in a surface hopping calculation.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

An integer between FSSH_LOWESTSURFACE and FSSH_LOWESTSURFACE $+$ FSSH_NSURFACES $-1$.


RECOMMENDATION:

None


FSSH_LOWESTSURFACE

Specifies the lowest-energy state considered in a surface hopping calculation.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

Only states $n$ and above are considered in a FSSH calculation.


RECOMMENDATION:

None


FSSH_NSURFACES

Specifies the number of states considered in a surface hopping calculation.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

$n$ states are considered in the surface hopping calculation.


RECOMMENDATION:

Any states which may come close in energy to the active surface should be included in the surface hopping calculation.


FTC_CLASS_THRESH_MULT

Together with FTC_CLASS_THRESH_ORDER, determines the cutoff threshold for included a shell-pair in the $dd$ class, i.e., the class that is expanded in terms of plane waves.


TYPE:

INTEGER


DEFAULT:

5

Multiplicative part of the FTC classification threshold. Together with

 

the default value of the FTC_CLASS_THRESH_ORDER this leads to

 

the $5\times 10^{-5}$ threshold value.


OPTIONS:

$n$

User specified.


RECOMMENDATION:

Use the default. If diffuse basis sets are used and the molecule is relatively big then tighter FTC classification threshold has to be used. According to our experiments using Pople-type diffuse basis sets, the default $5\times 10^{-5}$ value provides accurate result for an alanine5 molecule while $1\times 10^{-5}$ threshold value for alanine10 and $5\times 10^{-6}$ value for alanine15 has to be used.


FTC_CLASS_THRESH_ORDER

Together with FTC_CLASS_THRESH_MULT, determines the cutoff threshold for included a shell-pair in the $dd$ class, i.e., the class that is expanded in terms of plane waves.


TYPE:

INTEGER


DEFAULT:

5

Logarithmic part of the FTC classification threshold. Corresponds to $10^{-5}$


OPTIONS:

$n$

User specified


RECOMMENDATION:

Use the default.


FTC_SMALLMOL

Controls whether or not the operator is evaluated on a large grid and stored in memory to speed up the calculation.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

1

Use a big pre-calculated array to speed up the FTC calculations

0

Use this option to save some memory


RECOMMENDATION:

Use the default if possible and use 0 (or buy some more memory) when needed.


FTC

Controls the overall use of the FTC.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not use FTC in the Coulomb part

1

Use FTC in the Coulomb part


RECOMMENDATION:

Use FTC when bigger and/or diffuse basis sets are used.


GAUSSIAN_BLUR

Enables the use of Gaussian-delocalized external charges in a QM/MM calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Delocalizes external charges with Gaussian functions.

FALSE

Point charges


RECOMMENDATION:

None


GAUSS_BLUR_WIDTH

Delocalization width for external MM Gaussian charges in a Janus calculations.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$n$

Use a width of $n \times 10^{-4}$ Å.


RECOMMENDATION:

Blur all MM external charges in a QM/MM calculation with the specified width. Gaussian blurring is currently incompatible with PCM calculations. Values of 1.0–2.0 Å are recommended in Ref. Das:2002.


GEN_SCFMAN_ALGO_1

The first algorithm to be used in a hybrid-algorithm calculation.


TYPE:

STRING


DEFAULT:

0


OPTIONS:

All the available SCF_ALGORITHM options, including the GEN_SCFMAN additions (Section 4.3.1).


RECOMMENDATION:

None


GEN_SCFMAN_CONV_1

The convergence criterion given to the first algorithm. If reached, switch to the next algorithm.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

10$^{-n}$


RECOMMENDATION:

None


GEN_SCFMAN_HYBRID_ALGO

Use multiple algorithms in an SCF calculation based on GEN_SCFMAN.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Use a single SCF algorithm (given by SCF_ALGORITHM).

TRUE

Use multiple SCF algorithms (to be specified).


RECOMMENDATION:

Set it to TRUE when the use of more than one algorithm is desired.


GEN_SCFMAN_ITER_1

Maximum number of iterations given to the first algorithm. If used up, switch to the next algorithm.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

User-defined


RECOMMENDATION:

None


GEN_SCFMAN

Use GEN_SCFMAN for the present SCF calculation.


TYPE:

BOOLEAN


DEFAULT:

TRUE


OPTIONS:

FALSE

Use the previous SCF code.

TRUE

Use GEN_SCFMAN.


RECOMMENDATION:

Set to FALSE in cases where features not yet supported by GEN_SCFMAN are needed.


GEOM_OPT_CHARAC_CONV

Overide the built-in convergence criterion for the Davidson solver.


TYPE:

INTEGER


DEFAULT:

0 (use the built-in default value 10$^{-5}$)


OPTIONS:

$n$

Set the convergence criterion to 10$^{-n}$.


RECOMMENDATION:

Use the default. If it fails to converge, consider loosening the criterion with caution.


GEOM_OPT_CHARAC

Use the finite difference Davidson method to characterize the resulting energy minimum/transition state.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

do not characterize the resulting stationary point.

TRUE

perform a characterization of the stationary point.


RECOMMENDATION:

Set it to TRUE when the character of a stationary point needs to be verified, especially for a transition structure.


GEOM_OPT_COORDS

Controls the type of optimization coordinates.


TYPE:

INTEGER


DEFAULT:

$-$1


OPTIONS:

 0

Optimize in Cartesian coordinates.

 1

Generate and optimize in internal coordinates, if this fails abort.

$-$1

Generate and optimize in internal coordinates, if this fails at any stage of the

 

optimization, switch to Cartesian and continue.

 2

Optimize in $Z$-matrix coordinates, if this fails abort.

$-$2

Optimize in $Z$-matrix coordinates, if this fails during any stage of the

 

optimization switch to Cartesians and continue.


RECOMMENDATION:

Use the default; delocalized internals are more efficient.


GEOM_OPT_DMAX

Maximum allowed step size. Value supplied is multiplied by 10$^{-3}$.


TYPE:

INTEGER


DEFAULT:

300

= 0.3


OPTIONS:

$n$

User-defined cutoff.


RECOMMENDATION:

Use the default.


GEOM_OPT_HESSIAN

Determines the initial Hessian status.


TYPE:

STRING


DEFAULT:

DIAGONAL


OPTIONS:

DIAGONAL

Set up diagonal Hessian.

READ

Have exact or initial Hessian. Use as is if Cartesian, or transform

 

if internals.


RECOMMENDATION:

An accurate initial Hessian will improve the performance of the optimizer, but is expensive to compute.


GEOM_OPT_LINEAR_ANGLE

Threshold for near linear bond angles (degrees).


TYPE:

INTEGER


DEFAULT:

165 degrees.


OPTIONS:

$n$

User-defined level.


RECOMMENDATION:

Use the default.


GEOM_OPT_MAX_CYCLES

Maximum number of optimization cycles.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

User defined positive integer.


RECOMMENDATION:

The default should be sufficient for most cases. Increase if the initial guess geometry is poor, or for systems with shallow potential wells.


GEOM_OPT_MAX_DIIS

Controls maximum size of subspace for GDIIS.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not use GDIIS.

-1

Default size = min(NDEG, NATOMS, 4) NDEG = number of molecular

 

degrees of freedom.

$n$

Size specified by user.


RECOMMENDATION:

Use the default or do not set $n$ too large.


GEOM_OPT_MODE

Determines Hessian mode followed during a transition state search.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Mode following off.

$n$

Maximize along mode $n$.


RECOMMENDATION:

Use the default, for geometry optimizations.


GEOM_OPT_PRINT

Controls the amount of Optimize print output.


TYPE:

INTEGER


DEFAULT:

3

Error messages, summary, warning, standard information and gradient print out.


OPTIONS:

0

Error messages only.

1

Level 0 plus summary and warning print out.

2

Level 1 plus standard information.

3

Level 2 plus gradient print out.

4

Level 3 plus Hessian print out.

5

Level 4 plus iterative print out.

6

Level 5 plus internal generation print out.

7

Debug print out.


RECOMMENDATION:

Use the default.


GEOM_OPT_SYMFLAG

Controls the use of symmetry in Optimize.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Make use of point group symmetry.

FALSE

Do not make use of point group symmetry.


RECOMMENDATION:

Use the default.


GEOM_OPT_TOL_DISPLACEMENT

Convergence on maximum atomic displacement.


TYPE:

INTEGER


DEFAULT:

1200 $\equiv 1200 \times 10^{-6}$ tolerance on maximum atomic displacement.


OPTIONS:

$n$

Integer value (tolerance = $n \times 10^{-6}$).


RECOMMENDATION:

Use the default. To converge GEOM_OPT_TOL_GRADIENT and one of GEOM_OPT_TOL_DISPLACEMENT and GEOM_OPT_TOL_ENERGY must be satisfied.


GEOM_OPT_TOL_ENERGY

Convergence on energy change of successive optimization cycles.


TYPE:

INTEGER


DEFAULT:

100 $\equiv 100 \times 10^{-8}$ tolerance on maximum (absolute) energy change.


OPTIONS:

$n$ Integer value (tolerance = value $n \times 10^{-8}$).


RECOMMENDATION:

Use the default. To converge GEOM_OPT_TOL_GRADIENT and one of GEOM_OPT_TOL_DISPLACEMENT and GEOM_OPT_TOL_ENERGY must be satisfied.


GEOM_OPT_TOL_GRADIENT

Convergence on maximum gradient component.


TYPE:

INTEGER


DEFAULT:

300

$\equiv 300\times 10^{-6}$ tolerance on maximum gradient component.


OPTIONS:

$n$

Integer value (tolerance = $n \times 10^{-6}$).


RECOMMENDATION:

Use the default. To converge GEOM_OPT_TOL_GRADIENT and one of GEOM_OPT_TOL_DISPLACEMENT and GEOM_OPT_TOL_ENERGY must be satisfied.


GEOM_OPT_UPDATE

Controls the Hessian update algorithm.


TYPE:

INTEGER


DEFAULT:

-1


OPTIONS:

-1

Use the default update algorithm.

 0

Do not update the Hessian (not recommended).

 1

Murtagh-Sargent update.

 2

Powell update.

 3

Powell/Murtagh-Sargent update (TS default).

 4

BFGS update (OPT default).

 5

BFGS with safeguards to ensure retention of positive definiteness

 

(GDISS default).


RECOMMENDATION:

Use the default.


GEOM_PRINT

Controls the amount of geometric information printed at each step.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Prints out all geometric information; bond distances, angles, torsions.

FALSE

Normal printing of distance matrix.


RECOMMENDATION:

Use if you want to be able to quickly examine geometric parameters at the beginning and end of optimizations. Only prints in the beginning of single point energy calculations.


GHF

Run a generalized Hartree-Fock calculation with GEN_SCFMAN.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Run a GHF calculation.

FALSE

Do not use GHF.


RECOMMENDATION:

Set to TRUE if desired.


GRAIN

Controls the number of lowest-level boxes in one dimension for CFMM.


TYPE:

INTEGER


DEFAULT:

-1

Program decides best value, turning on CFMM when useful


OPTIONS:

-1

Program decides best value, turning on CFMM when useful

1

Do not use CFMM

$n\ge 8$

Use CFMM with $n$ lowest-level boxes in one dimension


RECOMMENDATION:

This is an expert option; either use the default, or use a value of 1 if CFMM is not desired.


GVB_AMP_SCALE

Scales the default orbital amplitude iteration step size by $n$/1000 for IP/RCC. PP amplitude equations are solved analytically, so this parameter does not affect PP.


TYPE:

INTEGER


DEFAULT:

1000

Corresponding to 100%


OPTIONS:

    $n$

User-defined, 0–1000


RECOMMENDATION:

Default is usually fine, but in some highly-correlated systems it can help with convergence to use smaller values.


GVB_DO_ROHF

Sets the number of Unrestricted-in-Active Pairs to be kept restricted.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-Defined


RECOMMENDATION:

If $n$ is the same value as GVB_N_PAIRS returns the ROHF solution for GVB, only works with the UNRESTRICTED = TRUE implementation of GVB with GVB_OLD_UPP = 0 (its default value)


GVB_DO_SANO

Sets the scheme used in determining the active virtual orbitals in a Unrestricted-in-Active Pairs GVB calculation.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

0

No localization or Sano procedure

1

Only localizes the active virtual orbitals

2

Uses the Sano procedure


RECOMMENDATION:

Different initial guesses can sometimes lead to different solutions. Disabling sometimes can aid in finding more non-local solutions for the orbitals.


GVB_GUESS_MIX

Similar to SCF_GUESS_MIX, it breaks alpha/beta symmetry for UPP by mixing the alpha HOMO and LUMO orbitals according to the user-defined fraction of LUMO to add the HOMO. 100 corresponds to a 1:1 ratio of HOMO and LUMO in the mixed orbitals.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined, $0 \le n \le 100$


RECOMMENDATION:

25 often works well to break symmetry without overly impeding convergence.


GVB_LOCAL

Sets the localization scheme used in the initial guess wave function.


TYPE:

INTEGER


DEFAULT:

2

Pipek-Mezey orbitals


OPTIONS:

0

No Localization

1

Boys localized orbitals

2

Pipek-Mezey orbitals


RECOMMENDATION:

Different initial guesses can sometimes lead to different solutions. It can be helpful to try both to ensure the global minimum has been found.


GVB_N_PAIRS

Alternative to CC_REST_OCC and CC_REST_VIR for setting active space size in GVB and valence coupled cluster methods.


TYPE:

INTEGER


DEFAULT:

PP active space (1 occ and 1 virt for each valence electron pair)


OPTIONS:

$n$

user-defined


RECOMMENDATION:

Use the default unless one wants to study a special active space. When using small active spaces, it is important to ensure that the proper orbitals are incorporated in the active space. If not, use the $reorder_mo feature to adjust the SCF orbitals appropriately.


GVB_OLD_UPP

Which unrestricted algorithm to use for GVB.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use Unrestricted-in-Active Pairs described in Ref. Lawler:2010

1

Use Unrestricted Implementation described in Ref. Beran:2005


RECOMMENDATION:

Only works for Unrestricted PP and no other GVB model.


GVB_ORB_CONV

The GVB-CC wave function is considered converged when the root-mean-square orbital gradient and orbital step sizes are less than $10^{-\ensuremath{\mathrm{GVB\_ ORB\_ CONV}}}$. Adjust THRESH simultaneously.


TYPE:

INTEGER


DEFAULT:

5


OPTIONS:

$n$

User-defined


RECOMMENDATION:

Use 6 for PP(2) jobs or geometry optimizations. Tighter convergence (i.e. 7 or higher) cannot always be reliably achieved.


GVB_ORB_MAX_ITER

Controls the number of orbital iterations allowed in GVB-CC calculations. Some jobs, particularly unrestricted PP jobs can require 500–1000 iterations.


TYPE:

INTEGER


DEFAULT:

256


OPTIONS:

User-defined number of iterations.


RECOMMENDATION:

Default is typically adequate, but some jobs, particularly UPP jobs, can require 500–1000 iterations if converged tightly.


GVB_ORB_SCALE

Scales the default orbital step size by $n$/1000.


TYPE:

INTEGER


DEFAULT:

1000

Corresponding to 100%


OPTIONS:

    $n$

User-defined, 0–1000


RECOMMENDATION:

Default is usually fine, but for some stretched geometries it can help with convergence to use smaller values.


GVB_POWER

Coefficient for GVB_IP exchange type amplitude regularization to improve the convergence of the amplitude equations especially for spin-unrestricted amplitudes near dissociation. This is the leading coefficient for an amplitude dampening term included in the energy denominator: -($c$/10000)$(e^{t_{ij}^ p}-1)/(e^1-1)$


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$p$

User-defined


RECOMMENDATION:

Should be decreased if unrestricted amplitudes do not converge or converge slowly at dissociation, and should be kept even valued.


GVB_PRINT

Controls the amount of information printed during a GVB-CC job.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined


RECOMMENDATION:

Should never need to go above 0 or 1.


GVB_REGULARIZE

Coefficient for GVB_IP exchange type amplitude regularization to improve the convergence of the amplitude equations especially for spin-unrestricted amplitudes near dissociation. This is the leading coefficient for an amplitude dampening term ${-(c/10000)(e^{t_{ij}^ p}-1)/(e^1-1)}$


TYPE:

INTEGER


DEFAULT:

0

For restricted

1

For unrestricted


OPTIONS:

$c$

User-defined


RECOMMENDATION:

Should be increased if unrestricted amplitudes do not converge or converge slowly at dissociation. Set this to zero to remove all dynamically-valued amplitude regularization.


GVB_REORDER_1

Tells the code which two pairs to swap first.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined XXXYYY


RECOMMENDATION:

This is in the format of two 3-digit pair indices that tell the code to swap pair XXX with YYY, for example swapping pair 1 and 2 would get the input 001002. Must be specified in GVB_REORDER_PAIRS $\ge $ 1.


GVB_REORDER_2

Tells the code which two pairs to swap second.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined XXXYYY


RECOMMENDATION:

This is in the format of two 3-digit pair indices that tell the code to swap pair XXX with YYY, for example swapping pair 1 and 2 would get the input 001002. Must be specified in GVB_REORDER_PAIRS $\ge $ 2.


GVB_REORDER_3

Tells the code which two pairs to swap third.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined XXXYYY


RECOMMENDATION:

This is in the format of two 3-digit pair indices that tell the code to swap pair XXX with YYY, for example swapping pair 1 and 2 would get the input 001002. Must be specified in GVB_REORDER_PAIRS $\ge $ 3.


GVB_REORDER_4

Tells the code which two pairs to swap fourth.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined XXXYYY


RECOMMENDATION:

This is in the format of two 3-digit pair indices that tell the code to swap pair XXX with YYY, for example swapping pair 1 and 2 would get the input 001002. Must be specified in GVB_REORDER_PAIRS $\ge $ 4.


GVB_REORDER_5

Tells the code which two pairs to swap fifth.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined XXXYYY


RECOMMENDATION:

This is in the format of two 3-digit pair indices that tell the code to swap pair XXX with YYY, for example swapping pair 1 and 2 would get the input 001002. Must be specified in GVB_REORDER_PAIRS $\ge $ 5.


GVB_REORDER_PAIRS

Tells the code how many GVB pairs to switch around.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

$0 \le n \le 5$


RECOMMENDATION:

This allows for the user to change the order the active pairs are placed in after the orbitals are read in or are guessed using localization and the Sano procedure. Up to 5 sequential pair swaps can be made, but it is best to leave this alone.


GVB_RESTART

Restart a job from previously-converged GVB-CC orbitals.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Useful when trying to converge to the same GVB solution at slightly different geometries, for example.


GVB_SHIFT

Value for a statically valued energy shift in the energy denominator used to solve the coupled cluster amplitude equations, $n$/10000.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined


RECOMMENDATION:

Default is fine, can be used in lieu of the dynamically valued amplitude regularization if it does not aid convergence.


GVB_SYMFIX

Should GVB use a symmetry breaking fix.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

no symmetry breaking fix

1

symmetry breaking fix with virtual orbitals spanning the active space

2

symmetry breaking fix with virtual orbitals spanning the whole virtual space


RECOMMENDATION:

It is best to stick with type 1 to get a symmetry breaking correction with the best results coming from CORRELATION=NP and GVB_SYMFIX = 1.


GVB_SYMPEN

Sets the pre-factor for the amplitude regularization term for the SB amplitudes.


TYPE:

INTEGER


DEFAULT:

160


OPTIONS:

$\gamma $

User-defined


RECOMMENDATION:

Sets the pre-factor for the amplitude regularization term for the SB amplitudes: $-(\gamma /1000)(e^{(c*100)*t^2}-1)$.


GVB_SYMSCA

Sets the weight for the amplitude regularization term for the SB amplitudes.


TYPE:

INTEGER


DEFAULT:

125


OPTIONS:

$c$

User-defined


RECOMMENDATION:

Sets the weight for the amplitude regularization term for the SB amplitudes: $-(\gamma /1000)(e^{(c*100)*t^2}-1)$.


GVB_TRUNC_OCC

Controls how many pairs’ occupied orbitals are truncated from the GVB active space.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined


RECOMMENDATION:

This allows for asymmetric GVB active spaces removing the $n$ lowest energy occupied orbitals from the GVB active space while leaving their paired virtual orbitals in the active space. Only the models including the SIP and DIP amplitudes (ie NP and 2P) benefit from this all other models this equivalent to just reducing the total number of pairs.


GVB_TRUNC_VIR

Controls how many pairs’ virtual orbitals are truncated from the GVB active space.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined


RECOMMENDATION:

This allows for asymmetric GVB active spaces removing the $n$ highest energy occupied orbitals from the GVB active space while leaving their paired virtual orbitals in the active space. Only the models including the SIP and DIP amplitudes (ie NP and 2P) benefit from this all other models this equivalent to just reducing the total number of pairs.


GVB_UNRESTRICTED

Controls restricted versus unrestricted PP jobs. Usually handled automatically.


TYPE:

LOGICAL


DEFAULT:

same value as UNRESTRICTED


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Set this variable explicitly only to do a UPP job from an RHF or ROHF initial guess. Leave this variable alone and specify UNRESTRICTED = TRUE to access the new Unrestricted-in-Active-Pairs GVB code which can return an RHF or ROHF solution if used with GVB_DO_ROHF


HESS_AND_GRAD

Enables the evaluation of both analytical gradient and Hessian in a single job


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Evaluates both gradient and Hessian.

FALSE

Evaluates Hessian only.


RECOMMENDATION:

Use only in a frequency (and thus Hessian) evaluation.


HFPT_BASIS

Specifies the secondary basis in a HFPC/DFPC calculation.


TYPE:

STRING


DEFAULT:

None


OPTIONS:

None


RECOMMENDATION:

See reference for recommended basis set, functional, and grid pairings.


HFPT

Activates HFPC/DFPC calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

Single-point energy only


RECOMMENDATION:

Use Dual-Basis to capture large-basis effects at smaller basis cost. See reference for recommended basis set, functional, and grid pairings.


HF_LR

Sets the fraction of Hartree-Fock exchange at $r_{12}=\infty $.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

$n$

Corresponding to HF_LR = $n/1000$


RECOMMENDATION:

None


HF_SR

Sets the fraction of Hartree-Fock exchange at $r_{12}=0$.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

$n$

Corresponding to HF_SR = $n/1000$


RECOMMENDATION:

None


HIRSHFELD_CONV

Set different SCF convergence criterion for the calculation of the single-atom Hirshfeld calculations


TYPE:

INTEGER


DEFAULT:

same as SCF_CONVERGENCE


OPTIONS:

$n$

Corresponding to $10^{-n}$


RECOMMENDATION:

5


HIRSHFELD_READ

Switch to force reading in of isolated atomic densities.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Read in isolated atomic densities from previous Hirshfeld calculation from disk.

FALSE

Generate new isolated atomic densities.


RECOMMENDATION:

Use the default unless system is large. Note, atoms should be in the same order with same basis set used as in the previous Hirshfeld calculation (although coordinates can change). The previous calculation should be run with the -save switch.


HIRSHFELD_SPHAVG

Controls whether atomic densities should be spherically averaged in pro-molecule.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Spherically average atomic densities.

FALSE

Do not spherically average.


RECOMMENDATION:

Use the default.


HIRSHFELD

Controls running of Hirshfeld population analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculate Hirshfeld populations.

FALSE

Do not calculate Hirshfeld populations.


RECOMMENDATION:

None


HIRSHITER_THRESH

Controls the convergence criterion of iterative Hirshfeld population analysis.


TYPE:

INTEGER


DEFAULT:

5


OPTIONS:

$N$

Corresponding to the convergence criterion of $N/10000$, in $e$.


RECOMMENDATION:

Use the default, which is the value recommended in Ref. Bultinck:2007


HIRSHITER

Controls running of iterative Hirshfeld population analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculate iterative Hirshfeld populations.

FALSE

Do not calculate iterative Hirshfeld populations.


RECOMMENDATION:

None


HIRSHMOD

Apply modifiers to the free-atom volumes used in the calculation of the scaled TS-vdW parameters


TYPE:

INTEGER


DEFAULT:

4


OPTIONS:

0

Do not apply modifiers to the Hirshfeld volumes.

1

Apply built-in modifier to H.

2

Apply built-in modifier to H and C.

3

Apply built-in modifier to H, C and N.

4

Apply built-in modifier to H, C, N and O


RECOMMENDATION:

Use the default


IDERIV

Controls the order of derivatives that are evaluated analytically. The user is not normally required to specify a value, unless numerical derivatives are desired. The derivatives will be evaluated numerically if IDERIV is set lower than JOBTYPE requires.


TYPE:

INTEGER


DEFAULT:

 

Set to the order of derivative that JOBTYPE requires


OPTIONS:

2

Analytic second derivatives of the energy (Hessian)

1

Analytic first derivatives of the energy.

0

Analytic energies only.


RECOMMENDATION:

Usually set to the maximum possible for efficiency. Note that IDERIV will be set lower if analytic derivatives of the requested order are not available.


IGDEFIELD

Triggers the calculation of the electrostatic potential and/or the electric field at the positions of the MM charges.


TYPE:

INTEGER


DEFAULT:

UNDEFINED


OPTIONS:

O

Computes ESP.

1

Computes ESP and EFIELD.

2

Computes EFIELD.


RECOMMENDATION:

Must use this $rem when IGDESP is specified.


IGDESP

Controls evaluation of the electrostatic potential on a grid of points. If enabled, the output is in an ASCII file, plot.esp, in the format $x, y, z,$ esp for each point.


TYPE:

INTEGER


DEFAULT:

none no electrostatic potential evaluation


OPTIONS:

$-2$

same as the option ’-1’, plus evaluate the ESP of $external_charges$

$-1$

read grid input via the $plots section of the input deck

$0$

Generate the ESP values at all nuclear positions

+$n$

read $n$ grid points in bohr from the ASCII file ESPGrid


RECOMMENDATION:

None


IGNORE_LOW_FREQ

Low frequencies that should be treated as rotation can be ignored during

anharmonic correction calculation.


TYPE:

INTEGER


DEFAULT:

300

Corresponding to 300 cm$^{-1}$.


OPTIONS:

$n$

Any mode with harmonic frequency less than $n$ will be ignored.


RECOMMENDATION:

Use the default.


INCDFT_DENDIFF_THRESH

Sets the threshold for screening density matrix values in the IncDFT procedure.


TYPE:

INTEGER


DEFAULT:

SCF_CONVERGENCE + 3


OPTIONS:

$n$

Corresponding to a threshold of $10^{-n}$.


RECOMMENDATION:

If the default value causes convergence problems, set this value higher to tighten the threshold.


INCDFT_DENDIFF_VARTHRESH

Sets the lower bound for the variable threshold for screening density matrix values in the IncDFT procedure. The threshold will begin at this value and then vary depending on the error in the current SCF iteration until the value specified by INCDFT_DENDIFF_THRESH is reached. This means this value must be set lower than INCDFT_DENDIFF_THRESH.


TYPE:

INTEGER


DEFAULT:

0

Variable threshold is not used.


OPTIONS:

$n$

Corresponding to a threshold of $10^{-n}$.


RECOMMENDATION:

If the default value causes convergence problems, set this value higher to tighten accuracy. If this fails, set to 0 and use a static threshold.


INCDFT_GRIDDIFF_THRESH

Sets the threshold for screening functional values in the IncDFT procedure


TYPE:

INTEGER


DEFAULT:

SCF_CONVERGENCE + 3


OPTIONS:

$n$

Corresponding to a threshold of $10^{-n}$.


RECOMMENDATION:

If the default value causes convergence problems, set this value higher to tighten the threshold.


INCDFT_GRIDDIFF_VARTHRESH

Sets the lower bound for the variable threshold for screening the functional values in the IncDFT procedure. The threshold will begin at this value and then vary depending on the error in the current SCF iteration until the value specified by INCDFT_GRIDDIFF_THRESH is reached. This means that this value must be set lower than INCDFT_GRIDDIFF_THRESH.


TYPE:

INTEGER


DEFAULT:

0

Variable threshold is not used.


OPTIONS:

$n$

Corresponding to a threshold of $10^{-n}$.


RECOMMENDATION:

If the default value causes convergence problems, set this value higher to tighten accuracy. If this fails, set to 0 and use a static threshold.


INCDFT

Toggles the use of the IncDFT procedure for DFT energy calculations.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

FALSE

Do not use IncDFT

TRUE

Use IncDFT


RECOMMENDATION:

Turning this option on can lead to faster SCF calculations, particularly towards the end of the SCF. Please note that for some systems use of this option may lead to convergence problems.


INCFOCK

Iteration number after which the incremental Fock matrix algorithm is initiated


TYPE:

INTEGER


DEFAULT:

1

Start INCFOCK after iteration number 1


OPTIONS:

User-defined (0 switches INCFOCK off)


RECOMMENDATION:

May be necessary to allow several iterations before switching on INCFOCK.


INTEGRALS_BUFFER

Controls the size of in-core integral storage buffer.


TYPE:

INTEGER


DEFAULT:

15

15 Megabytes.


OPTIONS:

User defined size.


RECOMMENDATION:

Use the default, or consult your systems administrator for hardware limits.


INTEGRAL_2E_OPR

Determines the two-electron operator.


TYPE:

INTEGER


DEFAULT:

-2

Coulomb Operator.


OPTIONS:

-1

Apply the CASE approximation.

-2

Coulomb Operator.


RECOMMENDATION:

Use the default unless the CASE operator is desired.


INTERNAL_STABILITY_CONV

Convergence criterion for the Davidson solver (for the lowest eigenvalues).


TYPE:

INTEGER


DEFAULT:

4 (3 when FD_MAT_ON_VECS = TRUE)


OPTIONS:

$n$

Terminate Davidson iterations when the norm of the residual vector is below 10$^{-n}$.


RECOMMENDATION:

Use the default.


INTERNAL_STABILITY_DAVIDSON_ITER

Maximum number of Davidson iterations allowed in one stability analysis.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

Perform up to $n$ Davidson iterations.


RECOMMENDATION:

Use the default.


INTERNAL_STABILITY_ITER

Maximum number of new SCF calculations permitted after the first stability analysis is performed.


TYPE:

INTEGER


DEFAULT:

0 (automatically set to 1 if INTERNAL_STABILITY = TRUE)


OPTIONS:

$n$

$n$ new SCF calculations permitted.


RECOMMENDATION:

Give a larger number if 1 is not enough (still unstable).


INTERNAL_STABILITY_ROOTS

Number of lowest Hessian eigenvalues to solve for.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$n$

Solve for $n$ lowest eigenvalues.


RECOMMENDATION:

Use the default.


INTERNAL_STABILITY

Perform internal stability analysis in GEN_SCFMAN.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform internal stability analysis after convergence.

TRUE

Perform internal stability analysis and generate the corrected MOs.


RECOMMENDATION:

Turn it on when the SCF solution is prone to unstable solutions, especially for open-shell species.


INTRACULE

Controls whether intracule properties are calculated (see also the $intracule section).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

No intracule properties.

TRUE

Evaluate intracule properties.


RECOMMENDATION:

None


IP_STATES

Sets the number of ionized target states roots to find. By default, $\beta $ electron will be removed (see EOM_IP_BETA).


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

0

Do not look for any IP states.


OPTIONS:

$[i,j,k\ldots ]$

Find $i$ ionized states in the first irrep, $j$ states in the second irrep etc.


RECOMMENDATION:

None


ISOTOPES

Specifies if non-default masses are to be used in the frequency calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Use default masses only.

TRUE

Read isotope masses from $isotopes section.


RECOMMENDATION:

None


JOBTYPE

Specifies the calculation.


TYPE:

STRING


DEFAULT:

Default is single-point, which should be changed to one of the following options.


OPTIONS:

OPT

Equilibrium structure optimization.

TS

Transition structure optimization.

RPATH

Intrinsic reaction path following.


RECOMMENDATION:

Application-dependent.


KS_GAP_PRINT

Control printing of (generalized Kohn-Sham) HOMO-LUMO gap information.


TYPE:

Boolean


DEFAULT:

false


OPTIONS:

false

(default) do not print gap information

true

print gap information


RECOMMENDATION:

Use in conjunction with KS_GAP_UNIT if true.


KS_GAP_UNIT

Unit for KS_GAP_PRINT and FOA_FUNDGAP (see Section 5.11)


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

(default) hartrees

1

eV


RECOMMENDATION:

none


LB94_BETA

Sets the $\beta $ parameter for the LB94 XC potential


TYPE:

INTEGER


DEFAULT:

500


OPTIONS:

$n$

Corresponding to $\beta = n/10000$.


RECOMMENDATION:

Use the default.


LINK_ATOM_PROJECTION

Controls whether to perform a link-atom projection


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Performs the projection

FALSE

No projection


RECOMMENDATION:

Necessary in a full QM/MM Hessian evaluation on a system with link atoms


LIN_K

Controls whether linear scaling evaluation of exact exchange (LinK) is used.


TYPE:

LOGICAL


DEFAULT:

Program chooses, switching on LinK whenever CFMM is used.


OPTIONS:

TRUE

Use LinK

FALSE

Do not use LinK


RECOMMENDATION:

Use for HF and hybrid DFT calculations with large numbers of atoms.


LOBA_THRESH

Specifies the thresholds to use for LOBA


TYPE:

INTEGER


DEFAULT:

6015


OPTIONS:

$aabb$

$aa$ specifies the threshold to use for localization

 

$bb$ specifies the threshold to use for occupation

 

Both are given as percentages.


RECOMMENDATION:

Decrease $bb$ to see the smaller contributions to orbitals. Values of $aa$ between 40 and 75 have been shown to given meaningful results.


LOBA

Specifies the methods to use for LOBA


TYPE:

INTEGER


DEFAULT:

00


OPTIONS:

$ab$

 

$a$

specifies the localization method

 

0 Perform Boys localization.

 

1 Perform PM localization.

 

2 Perform ER localization.

$b$

specifies the population analysis method

 

0 Do not perform LOBA. This is the default.

 

1 Use Mulliken population analysis.

 

2 Use Löwdin population analysis.


RECOMMENDATION:

Boys Localization is the fastest. ER will require an auxiliary basis set.

LOBA 12 provides a reasonable speed/accuracy compromise.


LOCALFREQ_GROUP1

Select the number of modes to include in the first subset of modes to localize independently when the keyword LOCALFREQ_GROUPS > 0.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$n$

User-specified integer.


RECOMMENDATION:

Modes will be included starting with the lowest frequency mode and then in ascending energy order up to the defined value.


LOCALFREQ_GROUPS

Select the number of groups of frequencies to be localized separately within a localized mode calculation. The size of the groups are then controlled using the LOCALFREQ_GROUP1, LOCALFREQ_GROUP2, and LOCALFREQ_GROUP3 keywords.


TYPE:

INTEGER


DEFAULT:

0

Localize all normal modes together.


OPTIONS:

1

Define one subset of modes to localize independently.

2

Define two subsets of modes to localize independently.

3

Define three subsets of modes to localize independently.


RECOMMENDATION:

None


LOCALFREQ_MAX_ITER

Controls the maximum number of mode localization sweeps permitted.


TYPE:

INTEGER


DEFAULT:

200


OPTIONS:

$n$

User-specified integer.


RECOMMENDATION:

None


LOCALFREQ_SELECT

Select a subset of normal modes for subsequent anharmonic frequency analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE

Use all normal modes.


OPTIONS:

TRUE

Select a subset of normal modes.


RECOMMENDATION:

None


LOCALFREQ_THRESH

Mode localization is considered converged when the change in the localization criterion is less than $10^\ensuremath{\mathrm{}}{-LOCALFREQ\_ THRESH}$.


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$n$

User-specified integer.


RECOMMENDATION:

None


LOCAL_FREQ

Controls whether a vibrational mode localization calculation is performed.


TYPE:

INTEGER


DEFAULT:

0

Normal mode calculation.


OPTIONS:

1

Localized mode calculation with a Pipek-Mezey like criterion.

2

Localized mode calculation with a Boys like criterion.


RECOMMENDATION:

None


LOCAL_INTERP_ORDER

Controls the order of the B-spline


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$n$

An integer


RECOMMENDATION:

The default value is sufficiently accurate


LOC_CIS_OV_SEPARATE

Decide whether or not to localized the “occupied” and “virtual” components of the localized diabatization function, i.e., whether to localize the electron attachments and detachments separately.


TYPE:

LOGICAL


DEFAULT:

FALSE

Do not separately localize electron attachments and detachments.


OPTIONS:

TRUE


RECOMMENDATION:

If one wants to use Boys localized diabatization for energy transfer (as opposed to electron transfer) , this is a necessary option. ER is more rigorous technique, and does not require this OV feature, but will be somewhat slower.


LOWDIN_POPULATION

Run Löwdin population analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not calculate Löwdin populations.

TRUE

Run Löwdin population analysis.


RECOMMENDATION:

None


LRC_DFT

Controls the application of long-range-corrected DFT


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Do not apply long-range correction.

TRUE (or 1)

Add 100% long-range Hartree-Fock exchange to the requested functional.


RECOMMENDATION:

The $rem variable OMEGA must also be specified, in order to set the range-separation parameter.


MAGNET

Activate the magnetic property module.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Don’t activate the magnetic property module.

TRUE (or 1)

Activate the magnetic property module.


RECOMMENDATION:

None.


MANY_BODY_BSSE

Controls the type of many-body BSSE corrections.


TYPE:

STRING


DEFAULT:

MBCP


OPTIONS:

MBCP

Use many-body counterpoise correction.

VMFC

Use Valiron-Mayer function counterpoise correction.


RECOMMENDATION:

NONE.


MANY_BODY_INT

Perform a MBE calculation.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform a MBE calculation.

FALSE

Do not perform a MBE calculation.


RECOMMENDATION:

NONE


MAX_CIS_CYCLES

Maximum number of CIS iterative cycles allowed.


TYPE:

INTEGER


DEFAULT:

30


OPTIONS:

$n$

User-defined number of cycles.


RECOMMENDATION:

Default is usually sufficient.


MAX_CIS_SUBSPACE

Maximum number of subspace vectors allowed in the CIS iterations


TYPE:

INTEGER


DEFAULT:

As many as required to converge all roots


OPTIONS:

$n$

User-defined number of subspace vectors


RECOMMENDATION:

The default is usually appropriate, unless a large number of states are requested for a large molecule. The total memory required to store the subspace vectors is bounded above by $2nOV$, where $O$ and $V$ represent the number of occupied and virtual orbitals, respectively. $n$ can be reduced to save memory, at the cost of a larger number of CIS iterations. Convergence may be impaired if $n$ is not much larger than CIS_N_ROOTS.


MAX_DIIS_CYCLES

The maximum number of DIIS iterations before switching to (geometric) direct minimization when SCF_ALGORITHM is DIIS_GDM or DIIS_DM. See also THRESH_DIIS_SWITCH.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

1

Only a single Roothaan step before switching to (G)DM

$n$

$n$ DIIS iterations before switching to (G)DM.


RECOMMENDATION:

None


MAX_RCA_CYCLES

The maximum number of RCA iterations before switching to DIIS when SCF_ALGORITHM is RCA_DIIS.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

N

N RCA iterations before switching to DIIS


RECOMMENDATION:

None


MAX_SCF_CYCLES

Controls the maximum number of SCF iterations permitted.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

$n>0$ User-selected.


RECOMMENDATION:

Increase for slowly converging systems such as those containing transition metals.


MBDVDW

Flag to switch on the MBD-vdW method


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not calculate MBD.

1

Calculate the MBD-vdW contribution to the energy.

2

Calculate the MBD-vdW contribution to the energy and the gradient.


RECOMMENDATION:

NONE


MBE_BSSE_ORDER

Controls the order of many-body BSSE corrections.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$n$

Order of many-body BSSE corrections


RECOMMENDATION:

MBCP and VMFC can be performed up to fourth order.


MBE_EMBEDDING

Controls the type of MBE calculations.


TYPE:

STRING


DEFAULT:

GAS


OPTIONS:

GAS

MBE without charge embedding.

CHARGES

MBE with charge embedding.


RECOMMENDATION:

NONE.


MBE_ORDER

Controls the truncation order $n$ for MBE.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$N$

Order of MBE


RECOMMENDATION:

MBE can be performed up to fifth order.


MECP_METHODS

Determines which method to be used.


TYPE:

STRING


DEFAULT:

BRANCHING_PLANE


OPTIONS:

BRANCHING_PLANE

Use the branching-plane updating method.

MECP_DIRECT

Use the direct method.

PENALTY_FUNCTION

Use the penalty-constrained method.


RECOMMENDATION:

The direct method is stable for small molecules or molecules with high symmetry. The branching-plane updating method is more efficient for larger molecules but does not work if the two states have different symmetries. If using the branching-plane updating method, GEOM_OPT_COORDS must be set to 0 in the $rem section, as this algorithm is available in Cartesian coordinates only. The penalty-constrained method converges slowly and is suggested only if other methods fail.


MECP_OPT

Determines whether we are doing MECP optimizations.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Do MECP optimization.

FALSE

Do not do MECP optimization.


RECOMMENDATION:

None.


MECP_PROJ_HESS

Determines whether to project out the coupling vector from the Hessian when using branching plane updating method.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

FALSE


RECOMMENDATION:

Use the default.


MECP_STATE1

Sets the first Born-Oppenheimer state for MECP optimization.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

None


OPTIONS:

[$i$,$j$]

Find the $j$th excited state with the total spin $i$; $j=0$ means the SCF ground state.


RECOMMENDATION:

$i$ is ignored for restricted calculations; for unrestricted calculations, $i$ can only be 0 or 1.


MECP_STATE2

Sets the second Born-Oppenheimer state for MECP optimization.


TYPE:

INTEGER/INTEGER ARRAY


DEFAULT:

None


OPTIONS:

[$i$,$j$]

Find the $j$th excited state with the total spin $i$; $j=0$ means the SCF ground state.


RECOMMENDATION:

$i$ is ignored for restricted calculations; for unrestricted calculations, $i$ can only be 0 or 1.


MEM_STATIC

Sets the memory for AO-integral evaluations and their transformations.


TYPE:

INTEGER


DEFAULT:

64

corresponding to 64 Mb.


OPTIONS:

$n$

User-defined number of megabytes.


RECOMMENDATION:

For RI-MP2 calculations, $150(ON + V)$ of MEM_STATIC is required. Because a number of matrices with $N^2$ size also need to be stored, 32–160 Mb of additional MEM_STATIC is needed.


MEM_TOTAL

Sets the total memory available to Q-Chem, in megabytes.


TYPE:

INTEGER


DEFAULT:

2000

2 Gb


OPTIONS:

$n$

User-defined number of megabytes.


RECOMMENDATION:

Use the default, or set to the physical memory of your machine. The minimum requirement is $3X^2$.


METECO

Sets the threshold criteria for discarding shell-pairs.


TYPE:

INTEGER


DEFAULT:

2

Discard shell-pairs below $10^{-\mathrm{THRESH}}$.


OPTIONS:

1

Discard shell-pairs four orders of magnitude below machine precision.

2

Discard shell-pairs below 10$^{-\mathrm{THRESH}}$.


RECOMMENDATION:

Use the default.


METHOD

Specifies the exchange-correlation functional.


TYPE:

STRING


DEFAULT:

No default


OPTIONS:

NAME

Use METHOD = NAME, where NAME is either HF for Hartree-Fock theory or

 

else one of the DFT methods listed in Section 5.3.4.


RECOMMENDATION:

In general, consult the literature to guide your selection. Our recommendations for DFT are indicated in bold in Section 5.3.4.


MGC_AMODEL

Choice of approximate cluster model.


TYPE:

INTEGER


DEFAULT:

Determines

how the CC equations are approximated:


OPTIONS:

0

Local Active-Space Amplitude iterations (pre-calculate GVB orbitals with your method of choice (RPP is good)).

7

Optimize-Orbitals using the VOD 2-step solver.

 

(Experimental-only use with MGC_AMPS = 2, 24 ,246)

8

Traditional Coupled Cluster up to CCSDTQPH.

9

MR-CC version of the Pair-Models. (Experimental)


RECOMMENDATION:

None


MGC_AMPS

Choice of Amplitude Truncation


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

2$\leq $ n $\leq $ 123456, a sorted list of integers for every amplitude

which will be iterated. Choose 1234 for PQ and 123456 for PH


RECOMMENDATION:

None


MGC_LOCALINTER

Pair filter on an intermediate.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

Any nonzero value enforces the pair constraint on intermediates,

significantly reducing computational cost. Not recommended for $\leq $ 2 pair locality


RECOMMENDATION:

None


MGC_LOCALINTS

Pair filter on an integrals.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

Enforces a pair filter on the 2-electron integrals, significantly

reducing computational cost. Generally useful. for more than 1 pair locality.


RECOMMENDATION:

None


MGC_NLPAIRS

Number of local pairs on an amplitude.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

Must be greater than 1, which corresponds to the PP model. 2 for PQ, and 3 for PH.


RECOMMENDATION:

None


MGEMM_THRESH

Sets MGEMM threshold to determine the separation between “large” and “small” matrix elements. A larger threshold value will result in a value closer to the single-precision result. Note that the desired factor should be multiplied by 10000 to ensure an integer value.


TYPE:

INTEGER


DEFAULT:

10000

(corresponds to 1)


OPTIONS:

$n$

User-specified threshold


RECOMMENDATION:

For small molecules and basis sets up to triple-$\zeta $, the default value suffices to not deviate too much from the double-precision values. Care should be taken to reduce this number for larger molecules and also larger basis-sets.


MI_ACTIVE_FRAGMENT

Sets the active fragment


TYPE:

INTEGER


DEFAULT:

NO DEFAULT


OPTIONS:

$n$

Specify the fragment on which the TDDFT calculation is to be performed, for LEA-TDDFT(MI).


RECOMMENDATION:

None


MI_LEA

Controls the LEA-TDDFT(MI) methods


TYPE:

INTEGER


DEFAULT:

NO DEFAULT


OPTIONS:

0

The LEA0 method

1

The LEA-Q method

2

The LEAc method


RECOMMENDATION:

1


MM_CHARGES

Requests the calculation of multipole-derived charges (MDCs).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Calculates the MDCs and also the traceless form of the multipole moments


RECOMMENDATION:

Set to TRUE if MDCs or the traceless form of the multipole moments are desired. The calculation does not take long.


MM_SUBTRACTIVE

Specifies whether a subtractive scheme is used in the $E_\ensuremath{\mathrm{}}{Coul}$, Eq. eq:ECoul, portion of the calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Only pairs that are not 1-2, 1-3, or 1-4 pairs are used.

TRUE

All pairs are calculated, and then the pairs that are double counted (1-2, 1-3, and 1-4) are subtracted out.


RECOMMENDATION:

When running QM/MM or MM calculations there is not recommendation. When running a QM/MM Ewald calculation the value must be set to TRUE.


MODEL_SYSTEM_CHARGE

Specifies the QM subsystem charge if different from the $molecule section.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$n$

The charge of the QM subsystem.


RECOMMENDATION:

This option only needs to be used if the QM subsystem (model system) has a charge that is different from the total system charge.


MODEL_SYSTEM_MULT

Specifies the QM subsystem multiplicity if different from the $molecule section.


TYPE:

INTEGER


DEFAULT:

NONE


OPTIONS:

$n$

The multiplicity of the QM subsystem.


RECOMMENDATION:

This option only needs to be used if the QM subsystem (model system) has a multiplicity that is different from the total system multiplicity. ONIOM calculations must be closed shell.


MODE_COUPLING

Number of modes coupling in the third and fourth derivatives calculation.


TYPE:

INTEGER


DEFAULT:

2

for two modes coupling.


OPTIONS:

$n$

for $n$ modes coupling, Maximum value is 4.


RECOMMENDATION:

Use the default.


MOLDEN_FORMAT

Requests a MolDen-formatted input file containing information from a Q-Chem job.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Append MolDen input file at the end of the Q-Chem output file.


RECOMMENDATION:

None.


MOM_METHOD

Determines the target orbitals with which to maximize the overlap on each SCF cycle.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

3

Maximize overlap with the orbitals from the previous SCF cycle.

13

Maximize overlap with the initial guess orbitals.


RECOMMENDATION:

If appropriate guess orbitals can be obtained, then MOM_METHOD = 13 can provide more reliable convergence to the desired solution.


MOM_PRINT

Switches printing on within the MOM procedure.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Printing is turned off

TRUE

Printing is turned on.


RECOMMENDATION:

None


MOM_START

Determines when MOM is switched on to stabilize DIIS iterations.


TYPE:

INTEGER


DEFAULT:

0 (FALSE)


OPTIONS:

0 (FALSE)

MOM is not used

$n$

MOM begins on cycle $n$.


RECOMMENDATION:

Set to 1 if preservation of initial orbitals is desired. If MOM is to be used to aid convergence, an SCF without MOM should be run to determine when the SCF starts oscillating. MOM should be set to start just before the oscillations.


MOPROP_CONV_1ST

Sets the convergence criteria for CPSCF and 1st order TDSCF.


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$n<10$

Convergence threshold set to $10^{-n}$.


RECOMMENDATION:

None


MOPROP_CONV_2ND

Sets the convergence criterion for second-order TDSCF.


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$n<10$

Convergence threshold set to $10^{-n}$.


RECOMMENDATION:

None


MOPROP_DIIS_DIM_SS

Specified the DIIS subspace dimension.


TYPE:

INTEGER


DEFAULT:

20


OPTIONS:

0

No DIIS.

$n$

Use a subspace of dimension $n$.


RECOMMENDATION:

None


MOPROP_DIIS

Controls the use of Pulay’s DIIS in solving the CPSCF equations.


TYPE:

INTEGER


DEFAULT:

5


OPTIONS:

0

Turn off DIIS.

5

Turn on DIIS.


RECOMMENDATION:

None


MOPROP_ISSC_PRINT_REDUCED

Specifies whether the isotope-independent reduced coupling tensor $\mathbf{K}$ should be printed in addition to the isotope-dependent $\mathbf{J}$-tensor when calculating indirect nuclear spin-spin couplings.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not print $\mathbf{K}$.

TRUE

Print $\mathbf{K}$.


RECOMMENDATION:

None


MOPROP_ISSC_SKIP_DSO

Specifies whether to skip the calculation of the diamagnetic spin-orbit contribution to the indirect nuclear spin-spin coupling tensor.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Calculate diamagnetic spin-orbit contribution.

TRUE

Skip diamagnetic spin-orbit contribution.


RECOMMENDATION:

None


MOPROP_ISSC_SKIP_FC

Specifies whether to skip the calculation of the Fermi contact contribution to the indirect nuclear spin-spin coupling tensor.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Calculate Fermi contact contribution.

TRUE

Skip Fermi contact contribution.


RECOMMENDATION:

None


MOPROP_ISSC_SKIP_PSO

Specifies whether to skip the calculation of the paramagnetic spin-orbit contribution to the indirect nuclear spin-spin coupling tensor.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Calculate paramagnetic spin-orbit contribution.

TRUE

Skip paramagnetic spin-orbit contribution.


RECOMMENDATION:

None


MOPROP_ISSC_SKIP_SD

Specifies whether to skip the calculation of the spin-dipole contribution to the indirect nuclear spin-spin coupling tensor.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Calculate spin-dipole contribution.

TRUE

Skip spin-dipole contribution.


RECOMMENDATION:

None


MOPROP_MAXITER_1ST

The maximum number of iterations for CPSCF and first-order TDSCF.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

Set maximum number of iterations to $n$.


RECOMMENDATION:

Use the default.


MOPROP_MAXITER_2ND

The maximum number of iterations for second-order TDSCF.


TYPE:

INTEGER


DEFAULT:

50


OPTIONS:

$n$

Set maximum number of iterations to $n$.


RECOMMENDATION:

Use the default.


MOPROP_PERTNUM

Set the number of perturbed densities that will to be treated together.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

All at once.

$n$

Treat the perturbed densities batch-wise.


RECOMMENDATION:

Use the default. For large systems, limiting this number may be required to avoid memory exhaustion.


MOPROP_RESTART

Specifies the option for restarting MOProp calculations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Not a restart calculation.

1

Restart from a previous calculation using the same scratch directory.


RECOMMENDATION:

Need to also include "SCF_GUESS READ" and "SKIP_SCFMAN TRUE" to ensure the same set of MOs.


MOPROP

Specifies the job number for MOProp module.


TYPE:

INTEGER


DEFAULT:

0

Do not run the MOProp module.


OPTIONS:

1

NMR chemical shielding tensors.

2

Static polarizability.

3

Indirect nuclear spin–spin coupling tensors.

100

Dynamic polarizability.

101

First hyperpolarizability.

102

First hyperpolarizability, reading First order results from disk.

103

First hyperpolarizability using Wigner’s $2n+1$ rule.

104

First hyperpolarizability using Wigner’s $2n+1$ rule, reading

 

first order results from disk.


RECOMMENDATION:

None


MRXC_CLASS_THRESH_MULT

Controls the of smoothness precision


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$im$

An integer


RECOMMENDATION:

A prefactor in the threshold for MRXC error control: $im\times 10^{-io}$


MRXC_CLASS_THRESH_ORDER

Controls the of smoothness precision


TYPE:

INTEGER


DEFAULT:

6


OPTIONS:

$io$

An integer


RECOMMENDATION:

The exponent in the threshold of the MRXC error control: $im\times 10^{-io}$


MRXC

Controls the use of MRXC.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not use MRXC

1

Use MRXC in the evaluation of the XC part


RECOMMENDATION:

MRXC is very efficient for medium and large molecules, especially when medium and large basis sets are used.


MULTIPOLE_ORDER

Determines highest order of multipole moments to print if wave function analysis requested.


TYPE:

INTEGER


DEFAULT:

4


OPTIONS:

$n$

Calculate moments to $n$th order.


RECOMMENDATION:

Use the default unless higher multipoles are required.


NBO

Controls the use of the NBO package.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not invoke the NBO package.

1

Do invoke the NBO package, for the ground state.

2

Invoke the NBO package for the ground state, and also each

 

CIS, RPA, or TDDFT excited state.


RECOMMENDATION:

None


NL_CORRELATION

Specifies a non-local correlation functional that includes non-empirical dispersion.


TYPE:

STRING


DEFAULT:

None

No non-local correlation.


OPTIONS:

None

No non-local correlation

vdW-DF-04

the non-local part of vdW-DF-04

vdW-DF-10

the non-local part of vdW-DF-10 (also known as vdW-DF2)

VV09

the non-local part of VV09

VV10

the non-local part of VV10


RECOMMENDATION:

Do not forget to add the LSDA correlation (PW92 is recommended) when using vdW-DF-04, vdW-DF-10, or VV09. VV10 should be used with PBE correlation. Choose exchange functionals carefully: HF, rPW86, revPBE, and some of the LRC exchange functionals are among the recommended choices.


NL_GRID

Specifies the grid to use for non-local correlation.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

Same as for XC_GRID


RECOMMENDATION:

Use the default unless computational cost becomes prohibitive, in which case SG-0 may be used. XC_GRID should generally be finer than NL_GRID.


NL_VV_B

Sets the parameter $b$ in VV10. This parameter controls the short range behavior of the non-local correlation energy.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

$n$

Corresponding to $b = n/100$


RECOMMENDATION:

The optimal value depends strongly on the exchange functional used. $b = 5.9$ is recommended for rPW86. For further details see Ref. Vydrov:2010b.


NL_VV_C

Sets the parameter $C$ in VV09 and VV10. This parameter is fitted to asymptotic van der Waals $C_6$ coefficients.


TYPE:

INTEGER


DEFAULT:

89

for VV09

No default

for VV10


OPTIONS:

$n$

Corresponding to $C = n/10000$


RECOMMENDATION:

$C = 0.0093$ is recommended when a semi-local exchange functional is used. $C = 0.0089$ is recommended when a long-range corrected (LRC) hybrid functional is used. For further details see Ref. Vydrov:2010b.


NOCI_PRINT

Specify the debug print level of NOCI.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$n$

Positive integer


RECOMMENDATION:

Increase this for additional debug information.


NOSE_HOOVER_LENGTH

Sets the chain length for the Nosé-Hoover thermostat


TYPE:

INTEGER


DEFAULT:

none


OPTIONS:

$n$

Chain length of $n$ auxiliary variables


RECOMMENDATION:

Typically 3-6


NOSE_HOOVER_TIMESCALE

Sets the timescale (strength) of the Nosé-Hoover thermostat


TYPE:

INTEGER


DEFAULT:

none


OPTIONS:

$n$

Thermostat timescale, as $n$ fs


RECOMMENDATION:

Smaller values (roughly 100) equate to tighter thermostats but may inhibit rapid sampling. Larger values ($\geq 1000$) allow for more rapid sampling but may take longer to reach thermal equilibrium.


NTO_PAIRS

Controls the writing of hole/particle NTO pairs for excited state.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$N$

Write $N$ NTO pairs per excited state.


RECOMMENDATION:

If activated ($N > 0$), a minimum of two NTO pairs will be printed for each state. Increase the value of $N$ if additional NTOs are desired.


NVO_LIN_CONVERGENCE

Target error factor in the preconditioned conjugate gradient solver of the single-excitation amplitude equations.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

$n$

User–defined number.


RECOMMENDATION:

Solution of the single-excitation amplitude equations is considered converged if the maximum residual is less than $10^{-n}$ multiplied by the current DIIS error. For the ARS correction, $n$ is automatically set to 1 since the locally-projected DIIS error is normally several orders of magnitude smaller than the full DIIS error.


NVO_LIN_MAX_ITE

Maximum number of iterations in the preconditioned conjugate gradient solver of the single-excitation amplitude equations.


TYPE:

INTEGER


DEFAULT:

30


OPTIONS:

$n$

User–defined number of iterations.


RECOMMENDATION:

None.


NVO_METHOD

Sets method to be used to converge solution of the single-excitation amplitude equations.


TYPE:

INTEGER


DEFAULT:

9


OPTIONS:

$n$

User–defined number.


RECOMMENDATION:

This is an experimental option. Use the default.


NVO_TRUNCATE_DIST

Specifies which atomic blocks of the Fock matrix are used to construct the preconditioner.


TYPE:

INTEGER


DEFAULT:

-1


OPTIONS:

$n>0$

If distance between a pair of atoms is more than $n$ Ångstroms

 

do not include the atomic block.

-2

Do not use distance threshold, use NVO_TRUNCATE_PRECOND instead.

-1

Include all blocks.

0

Include diagonal blocks only.


RECOMMENDATION:

This option does not affect the final result. However, it affects the rate of the PCG algorithm convergence. For small systems, use the default.


NVO_TRUNCATE_PRECOND

Specifies which atomic blocks of the Fock matrix are used to construct the preconditioner. This variable is used only if NVO_TRUNCATE_DIST is set to $-2$.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$n$

If the maximum element in an atomic block is less than $10^{-n}$ do not include

 

the block.


RECOMMENDATION:

Use the default. Increasing $n$ improves convergence of the PCG algorithm but overall may slow down calculations.


NVO_UVV_MAXPWR

Controls convergence of the Taylor series when calculating the $U_{vv}$ block from the single-excitation amplitudes. If the series is not converged at the $n$th term, more expensive direct inversion is used to calculate the $U_{vv}$ block.


TYPE:

INTEGER


DEFAULT:

10


OPTIONS:

$n$

User–defined number.


RECOMMENDATION:

None.


NVO_UVV_PRECISION

Controls convergence of the Taylor series when calculating the $U_{vv}$ block from the single-excitation amplitudes. Series is considered converged when the maximum element of the term is less than $10^{-n}$.


TYPE:

INTEGER


DEFAULT:

11


OPTIONS:

$n$

User–defined number.


RECOMMENDATION:

NVO_UVV_PRECISION must be the same as or larger than THRESH.


N_FROZEN_CORE

Sets the number of frozen core orbitals in a post-Hartree–Fock calculation.


TYPE:

INTEGER


DEFAULT:

FC


OPTIONS:

FC

Frozen Core approximation (all core orbitals frozen).

$n$

Freeze $n$ core orbitals (if set to 0, all electrons will be active).


RECOMMENDATION:

Correlated calculations calculations are more efficient with frozen core orbitals. Use default if possible.


N_FROZEN_VIRTUAL

Sets the number of frozen virtual orbitals in a post-Hartree–Fock calculation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Freeze $n$ virtual orbitals.


RECOMMENDATION:

None


N_I_SERIES

Sets summation limit for series expansion evaluation of $i_ n(x)$.


TYPE:

INTEGER


DEFAULT:

40


OPTIONS:

$n>0$


RECOMMENDATION:

Lower values speed up the calculation, but may affect accuracy.


N_J_SERIES

Sets summation limit for series expansion evaluation of $j_ n(x)$.


TYPE:

INTEGER


DEFAULT:

40


OPTIONS:

$n>0$


RECOMMENDATION:

Lower values speed up the calculation, but may affect accuracy.


N_SOL

Specifies number of atoms included in the Hessian.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

User defined


RECOMMENDATION:

None


N_WIG_SERIES

Sets summation limit for Wigner integrals.


TYPE:

INTEGER


DEFAULT:

10


OPTIONS:

$n<100$


RECOMMENDATION:

Increase $n$ for greater accuracy.


OCCUPATIONS

Activates pFON calculation.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Integer occupation numbers

1

Not yet implemented

2

Pseudo-fractional occupation numbers (pFON)


RECOMMENDATION:

Use pFON to improve convergence for small-gap systems.


OCC_RI_K

Controls the use of the occ-RI-K approximation for constructing the exchange matrix


TYPE:

LOGICAL


DEFAULT:

False

Do not use occ-RI-K.


OPTIONS:

True

Use occ-RI-K.


RECOMMENDATION:

Larger the system, better the performance


OMEGA2

Sets the Coulomb attenuation parameter for the long-range component.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

$n$

Corresponding to $\omega 2 = n/1000$, in units of bohr$^{-1}$


RECOMMENDATION:

None


OMEGA_GDD_SCALING

Sets the empirical constant $C$ in $\omega ^{}_{\rm GDD}$ tuning procedure.


TYPE:

INTEGER


DEFAULT:

885


OPTIONS:

$n$

Corresponding to $C = n/1000$.


RECOMMENDATION:

The quantity $n$ = 885 was determined by Lao and Herbert in Ref. Lao:2018 using LRC-$\omega $PBE and def2-TZVPP augmented with diffuse functions on non-hydrogen atoms that are taken from Dunning’s aug-cc-pVTZ basis set.


OMEGA_GDD

Controls the application of $\omega ^{}_{\rm GDD}$ tuning for long-range-corrected DFT


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Do not apply $\omega ^{}_{\rm GDD}$ tuning.

TRUE (or 1)

Use $\omega ^{}_{\rm GDD}$ tuning.


RECOMMENDATION:

The $rem variable OMEGA must also be specified, in order to set the initial range-separation parameter.


OMEGA

Controls the degree of attenuation of the Coulomb operator.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

$n$

Corresponding to $\omega = n/1000$, in units of bohr$^{-1}$


RECOMMENDATION:

None


OMEGA

Sets the Coulomb attenuation parameter for the short-range component.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

$n$

Corresponding to $\omega = n/1000$, in units of bohr$^{-1}$


RECOMMENDATION:

None


OS_ROSCF

Run an open-shell singlet ROSCF calculation with GEN_SCFMAN.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

OS_ROSCF calculation is performed.

FALSE

Do not run OS_ROSCF (it will run a close-shell RSCF calculation instead).


RECOMMENDATION:

Set to TRUE if desired.


PAO_ALGORITHM

Algorithm used to optimize polarized atomic orbitals (see PAO_METHOD)


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use efficient (and riskier) strategy to converge PAOs.

1

Use conservative (and slower) strategy to converge PAOs.


RECOMMENDATION:

None


PAO_METHOD

Controls evaluation of polarized atomic orbitals (PAOs).


TYPE:

STRING


DEFAULT:

EPAO

For local MP2 calculations Otherwise no default.


OPTIONS:

PAO

Perform PAO-SCF instead of conventional SCF.

EPAO

Obtain EPAOs after a conventional SCF.


RECOMMENDATION:

None


PARI_K

Controls the use of the PARI-K approximation in the construction of the exchange matrix


TYPE:

LOGICAL


DEFAULT:

FALSE

Do not use PARI-K.


OPTIONS:

TRUE

Use PARI-K.


RECOMMENDATION:

Use for basis sets aug-cc-pVTZ and larger.


PBHT_ANALYSIS

Controls whether overlap analysis of electronic excitations is performed.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform overlap analysis.

TRUE

Perform overlap analysis.


RECOMMENDATION:

None


PBHT_FINE

Increases accuracy of overlap analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE

 

OPTIONS:

FALSE

 

TRUE

Increase accuracy of overlap analysis.


RECOMMENDATION:

None


PEQ_SWITCH

Inclusion of solvent effects begins when the SCF error falls below 10$^{-\rm PEQ\_ SWITCH}$.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

$n$

Corresponding to 10$^{-n}$


RECOMMENDATION:

Use the default unless solvent effects need to be incorporated earlier in the SCF procedure.


PHESS

Controls whether partial Hessian calculations are performed.


TYPE:

INTEGER


DEFAULT:

0

Full Hessian calculation


OPTIONS:

1

Partial Hessian calculation.

2

Vibrational subsystem analysis (massless).

3

Vibrational subsystem analysis (weighted).


RECOMMENDATION:

None


PH_FAST

Lowers integral cutoff in partial Hessian calculation is performed.


TYPE:

LOGICAL


DEFAULT:

FALSE

Use default cutoffs


OPTIONS:

TRUE

Lower integral cutoffs


RECOMMENDATION:

None


PIMC_ACCEPT_RATE

Acceptance rate for MC/PIMC simulations when Cartesian or normal-mode displacements are used.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$0 < n < 100$

User-specified rate, given as a whole-number percentage.


RECOMMENDATION:

Choose acceptance rate to maximize sampling efficiency, which is typically signified by the mean-square displacement (printed in the job output). Note that the maximum displacement is adjusted during the warm-up run to achieve roughly this acceptance rate.


PIMC_MCMAX

Number of Monte Carlo steps to sample.


TYPE:

INTEGER


DEFAULT:

None.


OPTIONS:
 

User-specified number of steps to sample.


RECOMMENDATION:

This variable dictates the statistical convergence of MC/PIMC simulations. For converged simulations at least $10^5$ steps is recommended.


PIMC_MOVETYPE

Selects the type of displacements used in MC/PIMC simulations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Cartesian displacements of all beads, with occasional (1%) center-of-mass moves.

1

Normal-mode displacements of all modes, with occasional (1%) center-of-mass moves.

2

Levy flights without center-of-mass moves.


RECOMMENDATION:

Except for classical sampling (MC) or small bead-number quantum sampling (PIMC), Levy flights should be used. For Cartesian and normal-mode moves, the maximum displacement is adjusted during the warm-up run to the desired acceptance rate (controlled by PIMC_ACCEPT_RATE). For Levy flights, the acceptance is solely controlled by PIMC_SNIP_LENGTH.


PIMC_NBEADSPERATOM

Number of path integral time slices (“beads”) used on each atom of a PIMC simulation.


TYPE:

INTEGER


DEFAULT:

None.


OPTIONS:

1

Perform classical Boltzmann sampling.

$>$1

Perform quantum-mechanical path integral sampling.


RECOMMENDATION:

This variable controls the inherent convergence of the path integral simulation. The one-bead limit represents classical sampling and the infinite-bead limit represents exact quantum-mechanical sampling. Using 32 beads is reasonably converged for room-temperature simulations of molecular systems.


PIMC_SNIP_LENGTH

Number of “beads” to use in the Levy flight movement of the ring polymer.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$3 \leq n \leq \mbox{{\small PIMC\_ NBEADSPERATOM}}$

User-specified length of snippet.


RECOMMENDATION:

Choose the snip length to maximize sampling efficiency. The efficiency can be estimated by the mean-square displacement between configurations, printed at the end of the output file. This efficiency will typically, however, be a trade-off between the mean-square displacement (length of statistical correlations) and the number of beads moved. Only the moved beads require recomputing the potential, i.e., a call to Q-Chem for the electronic energy. (Note that the endpoints of the snippet remain fixed during a single move, so $n-2$ beads are actually moved for a snip length of $n$. For 1 or 2 beads in the simulation, Cartesian moves should be used instead.)


PIMC_TEMP

Temperature, in Kelvin (K), of path integral simulations.


TYPE:

INTEGER


DEFAULT:

None.


OPTIONS:
 

User-specified number of Kelvin for PIMC or classical MC simulations.


RECOMMENDATION:

None.


PIMC_WARMUP_MCMAX

Number of Monte Carlo steps to sample during an equilibration period of MC/PIMC simulations.


TYPE:

INTEGER


DEFAULT:

None.


OPTIONS:
 

User-specified number of steps to sample.


RECOMMENDATION:

Use this variable to equilibrate the molecule/ring polymer before collecting production statistics. Usually a short run of roughly 10% of PIMC_MCMAX is sufficient.


PLOT_SPIN_DENSITY

Requests the generation of spin densities, $\rho _\alpha $ and $\rho _\beta $.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not generate spin density cube files.

TRUE

Generate spin density cube files.


RECOMMENDATION:

Set to TRUE if spin densities are desired in addition to total densities. Requires that MAKE_CUBE_FILES be set to TRUE as well, and that one or more total densities is requested in the $plots input section. The corresponding spin densities will then be generated also.


POL_GEOM

Compute forces on the polarized (converged SCFMI) PES.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not compute forces on the polarized PES.

TRUE

Compute forces on the polarized PES.


RECOMMENDATION:

Set it to TRUE when optimized geometry or vibrational frequencies on the polarized PES are desired.


POP_MULLIKEN

Controls running of Mulliken population analysis.


TYPE:

LOGICAL/INTEGER


DEFAULT:

TRUE (or 1)


OPTIONS:

FALSE (or 0)

Do not calculate Mulliken populations.

TRUE (or 1)

Calculate Mulliken populations.

2

Also calculate shell populations for each occupied orbital.

$-1$

Calculate Mulliken charges for both the ground state and any CIS,

 

RPA, or TDDFT excited states.


RECOMMENDATION:

Leave as TRUE, unless excited-state charges are desired. Mulliken analysis is a trivial additional calculation, for ground or excited states.


PRINT_CORE_CHARACTER

Determines the print level for the CORE_CHARACTER option.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

No additional output is printed.

1

Prints core characters of occupied MOs.

2

Print level 1, plus prints the core character of AOs.


RECOMMENDATION:

Use the default, unless you are uncertain about what the core character is.


PRINT_DIST_MATRIX

Controls the printing of the inter-atomic distance matrix


TYPE:

INTEGER


DEFAULT:

15


OPTIONS:

0

Turns off the printing of the distance matrix

$n$

Prints the distance matrix if the number of atoms in the molecule

 

is less than or equal to $n$.


RECOMMENDATION:

Use default unless distances are required for large systems


PRINT_GENERAL_BASIS

Controls print out of built in basis sets in input format


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Print out standard basis set information

FALSE

Do not print out standard basis set information


RECOMMENDATION:

Useful for modification of standard basis sets.


PRINT_ORBITALS

Prints orbital coefficients with atom labels in analysis part of output.


TYPE:

INTEGER/LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not print any orbitals.

TRUE

Prints occupied orbitals plus 5 virtual orbitals.

NVIRT

Number of virtual orbitals to print.


RECOMMENDATION:

Use true unless more virtual orbitals are desired.


PRINT_RADII_GYRE

Controls printing of MO centroids and radii of gyration.


TYPE:

LOGICAL/INTEGER


DEFAULT:

FALSE


OPTIONS:

TRUE (or 1)

Print the centroid and radius of gyration for each occupied MO and each density.

2

Print centroids and radii of gyration for the virtual MOs as well.

FALSE (or 0)

Do not calculate these quantities.


RECOMMENDATION:

None


PROJ_TRANSROT

Removes translational and rotational drift during AIMD trajectories.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not apply translation/rotation corrections.

TRUE

Apply translation/rotation corrections.


RECOMMENDATION:

When computing spectra (see AIMD_NUCL_DACF_POINTS, for example), this option can be used to remove artificial, contaminating peaks stemming from translational and/or rotational motion. Recommend setting to TRUE for all dynamics-based spectral simulations.


PSEUDO_CANONICAL

When SCF_ALGORITHM = DM, this controls the way the initial step, and steps after subspace resets are taken.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Use Roothaan steps when (re)initializing

TRUE

Use a steepest descent step when (re)initializing


RECOMMENDATION:

The default is usually more efficient, but choosing TRUE sometimes avoids problems with orbital reordering.


PURECART

INTEGER


TYPE:

Controls the use of pure (spherical harmonic) or Cartesian angular forms


DEFAULT:

2111

Cartesian $h$-functions and pure $g,f,d$ functions


OPTIONS:

$hgfd$

Use 1 for pure and 2 for Cartesian.


RECOMMENDATION:

This is pre-defined for all standard basis sets


QMMM_CHARGES

Controls the printing of QM charges to file.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Writes a charges.dat file with the Mulliken charges from the QM region.

FALSE

No file written.


RECOMMENDATION:

Use the default unless running calculations with Charmm where charges on the QM region need to be saved.


QMMM_FULL_HESSIAN

Trigger the evaluation of the full QM/MM Hessian.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Evaluates full Hessian.

FALSE

Hessian for QM-QM block only.


RECOMMENDATION:

None


QMMM_PRINT

Controls the amount of output printed from a QM/MM job.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Limit molecule, point charge, and analysis printing.

FALSE

Normal printing.


RECOMMENDATION:

Use the default unless running calculations with Charmm.


QM_MM_INTERFACE

Enables internal QM/MM calculations.


TYPE:

STRING


DEFAULT:

NONE


OPTIONS:

MM

Molecular mechanics calculation (i.e., no QM region)

ONIOM

QM/MM calculation using two-layer mechanical embedding

JANUS

QM/MM calculation using electronic embedding


RECOMMENDATION:

The ONIOM model and Janus models are described above. Choosing MM leads to no electronic structure calculation. However, when using MM, one still needs to define the $rem variables BASIS and EXCHANGE in order for Q-Chem to proceed smoothly.


QM_MM

Turns on the Q-Chem/Charmm interface.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Do QM/MM calculation through the Q-Chem/Charmm interface.

FALSE

Turn this feature off.


RECOMMENDATION:

Use the default unless running calculations with Charmm.


RAS_ACT_DIFF

Sets the number of alpha vs. beta electrons


TYPE:

Integer


DEFAULT:

None


OPTIONS:

n

user defined integer


RECOMMENDATION:

Set to 1 for an odd number of electrons or a cation, -1 for an anion. Only works with RASCI2.


RAS_ACT_OCC

Sets the number of occupied orbitals to enter the RAS active space.


TYPE:

Integer


DEFAULT:

None


OPTIONS:

n

user defined integer


RECOMMENDATION:

None. Only works with RASCI2


RAS_ACT_ORB

Sets the user-selected active orbitals (RAS2 orbitals).


TYPE:

INTEGER ARRAY


DEFAULT:

From RAS_OCC+1 to RAS_OCC+RAS_ACT


OPTIONS:

$[i,j,k...]$

The number of orbitals must be equal to the RAS_ACT variable


RECOMMENDATION:

None. Only works with RASCI.


RAS_ACT_VIR

Sets the number of virtual orbitals to enter the RAS active space.


TYPE:

Integer


DEFAULT:

None


OPTIONS:

n

user defined integer


RECOMMENDATION:

None. Only works with RASCI2.


RAS_ACT

Sets the number of orbitals in RAS2 (active orbitals).


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

User-defined integer, $n>0$


RECOMMENDATION:

None. Only works with RASCI.


RAS_AMPL_PRINT

Defines the absolute threshold ($\times 10^2$) for the CI amplitudes to be printed.


TYPE:

INTEGER


DEFAULT:

10

0.1 minimum absolute amplitude


OPTIONS:

$n$

User-defined integer, $n\geq 0$


RECOMMENDATION:

None. Only works with RASCI.


RAS_DO_HOLE

Controls the presence of hole excitations in the RAS-CI wave function.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Include hole configurations (RAS1 to RAS2 excitations)

FALSE

Do not include hole configurations


RECOMMENDATION:

None. Only works with RASCI.


RAS_DO_PART

Controls the presence of particle excitations in the RAS-CI wave function.


TYPE:

LOGICAL


DEFAULT:

TRUE


OPTIONS:

TRUE

Include particle configurations (RAS2 to RAS3 excitations)

FALSE

Do not include particle configurations


RECOMMENDATION:

None. Only works with RASCI.


RAS_ELEC

Sets the number of electrons in RAS2 (active electrons).


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

User-defined integer, $n>0$


RECOMMENDATION:

None. Only works with RASCI.


RAS_FRAG_SETS

Sets the number of atoms in each fragment.


TYPE:

INTEGER ARRAY


DEFAULT:

[NOcc,NAct,NVir]

Number of orbitals within RAS1, RAS2 and RAS3 spaces


OPTIONS:

$[i,j,k...]$

Defines sets of canonical MOs to be localized into $n$ fragments


RECOMMENDATION:

Setting within RAS1, RAS2 and RAS3 spaces alleviates the computational cost of the localization procedure. It might also result in improved fragment orbitals. Only works with RASCI.


RAS_GUESS_CS

Controls the number of closed shell guess configurations in RAS-CI.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Imposes to start with $n$ closed shell guesses


RECOMMENDATION:

Only relevant for the computation of singlet states. Only works with RASCI.


RAS_NATORB_STATE

Allows to save the natural orbitals of a RAS-CI computed state.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$i$

Saves the natural orbitals for the $i$-th state


RECOMMENDATION:

None. Only works with RASCI.


RAS_NATORB

Controls the computation of the natural orbital occupancies.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Compute natural orbital occupancies for all states

FALSE

Do not compute natural orbital occupancies


RECOMMENDATION:

None. Only works with RASCI.


RAS_NFRAG_ATOMS

Sets the number of atoms in each fragment.


TYPE:

INTEGER ARRAY


DEFAULT:

None


OPTIONS:

$[i,j,k...]$

The sum of the numbers must be equal to the total number of atoms in the systems


RECOMMENDATION:

None. Only works with RASCI.


RAS_NFRAG

If $n>0$ activates the excitation analysis in RASCI


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Number of fragments to be considered


RECOMMENDATION:

Only for RASCI. The printed information level is controlled by RAS_PRINT.


RAS_N_ROOTS

Sets the number of RAS-CI roots to be computed.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

$n>0$ Compute $n$ RAS-CI states


RECOMMENDATION:

None. Only works with RASCI2


RAS_OCC

Sets the number of orbitals in RAS1


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined integer, $n>0$


RECOMMENDATION:

These are the initial doubly occupied orbitals (RAS1) before including $hole$ type of excitations. The RAS1 space starts from the lowest orbital up to RAS_OCC, i.e. no frozen orbitals option available yet. Only works with RASCI.


RAS_PT2_PARTITION

Specifies the partitioning scheme in RASCI(2)


TYPE:

INTEGER


DEFAULT:

1

Davidson-Kapuy (DK) partitioning


OPTIONS:

2

Epstein-Nesbet (EN) partitioning

0

Do both DK and EN partitionings


RECOMMENDATION:

Only for RASCI if RAS_PT2 is set to true.


RAS_PT2_VSHIFT

Defines the energy level shift ($\times 10^3~ au$) in RASCI(2)


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

User-defined integer


RECOMMENDATION:

Only for RASCI if RAS_PT2 is set to true.


RAS_PT2

Perform second-order perturbative correction to RAS-CI energy


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Compute RASCI(2) energy corrections

FALSE

Do not compute RASCI(2) energy corrections


RECOMMENDATION:

None. Only works with RASCI.


RAS_ROOTS

Sets the number of RAS-CI roots to be computed.


TYPE:

INTEGER


DEFAULT:

None


OPTIONS:

$n$

$n>0$ Compute $n$ RAS-CI states


RECOMMENDATION:

None. Only works with RASCI.


RAS_SPIN_MULT

Specifies the spin multiplicity of the roots to be computed


TYPE:

INTEGER


DEFAULT:

1

Singlet states


OPTIONS:

0

Compute any spin multiplicity

$2n+1$

User-defined integer, $n\geq 0$


RECOMMENDATION:

Only for RASCI, which at present only allows for the computation of systems with an even number of electrons. Thus, RAS_SPIN_MULT only can take odd values.


RCA_PRINT

Controls the output from RCA SCF optimizations.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

No print out

1

RCA summary information

2

Level 1 plus RCA coefficients

3

Level 2 plus RCA iteration details


RECOMMENDATION:

None


RC_R0

Determines the parameter in the Gaussian weight function used to smooth the density at the nuclei.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Corresponds the traditional delta function spin and charge densities

$n$

corresponding to $n\times 10^{-3}$ a.u.


RECOMMENDATION:

We recommend value of 250 for a typical spit valence basis. For basis sets with increased flexibility in the nuclear vicinity the smaller values of $r_0$ also yield adequate spin density.


RESPONSE

Activate the general response property module.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE (or 0)

Don’t activate the general response property module.

TRUE (or 1)

Activate the general response property module.


RECOMMENDATION:

None.


RISAPT

Requests an RI-SAPT calculation


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Compute four-index integrals using the RI approximation.

FALSE

Do not use RI.


RECOMMENDATION:

Set to TRUE if an appropriate auxiliary basis set is available, as RI-SAPT is much faster and affords negligible errors (as compared to ordinary SAPT) if the auxiliary basis set is matched to the primary basis set. (The former must be specified using AUX_BASIS.)


RI_J

Toggles the use of the RI algorithm to compute J.


TYPE:

LOGICAL


DEFAULT:

FALSE

RI will not be used to compute J.


OPTIONS:

TRUE

Turn on RI for J.


RECOMMENDATION:

For large (especially 1D and 2D) molecules the approximation may yield significant improvements in Fock evaluation time when used with ARI.


RI_K_GRAD

Turn on the nuclear gradient calculations


TYPE:

LOGICAL


DEFAULT:

FALSE

Do not invoke occ-RI-K based gradient


OPTIONS:

TRUE

Use occ-RI-K based gradient


RECOMMENDATION:

Use "RI_J false"


RI_K

Toggles the use of the RI algorithm to compute K.


TYPE:

LOGICAL


DEFAULT:

FALSE

RI will not be used to compute K.


OPTIONS:

TRUE

Turn on RI for K.


RECOMMENDATION:

For large (especially 1D and 2D) molecules the approximation may yield significant improvements in Fock evaluation time when used with ARI.


ROKS_LEVEL_SHIFT

Introduce a level shift of N/100 hartree to aid convergence.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

No shift

N

level shift of N/100 hartree.


RECOMMENDATION:

Use in cases of problematic convergence.


ROKS

Controls whether ROKS calculation will be performed.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

ROKS is not performed.

TRUE

ROKS will be performed.


RECOMMENDATION:

Set to TRUE if ROKS calculation is desired. You should also set UNRESTRICTED = FALSE


RPATH_COORDS

Determines which coordinate system to use in the IRC search.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Use mass-weighted coordinates.

1

Use Cartesian coordinates.

2

Use Z-matrix coordinates.


RECOMMENDATION:

Use the default.


RPATH_DIRECTION

Determines the direction of the eigenmode to follow. This will not usually be known prior to the Hessian diagonalization.


TYPE:

INTEGER


DEFAULT:

 1


OPTIONS:

 1

Descend in the positive direction of the eigen mode.

-1

Descend in the negative direction of the eigen mode.


RECOMMENDATION:

It is usually not possible to determine in which direction to go a priori, and therefore both directions will need to be considered.


RPATH_MAX_CYCLES

Specifies the maximum number of points to find on the reaction path.


TYPE:

INTEGER


DEFAULT:

20


OPTIONS:

$n$

User-defined number of cycles.


RECOMMENDATION:

Use more points if the minimum is desired, but not reached using the default.


RPATH_MAX_STEPSIZE

Specifies the maximum step size to be taken (in 0.001 a.u.).


TYPE:

INTEGER


DEFAULT:

150

corresponding to a step size of 0.15 a.u..


OPTIONS:

$n$

Step size = $n$/1000 a.u.


RECOMMENDATION:

None.


RPATH_PRINT

Specifies the print output level.


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

$n$


RECOMMENDATION:

Use the default, as little additional information is printed at higher levels. Most of the output arises from the multiple single point calculations that are performed along the reaction pathway.


RPATH_TOL_DISPLACEMENT

Specifies the convergence threshold for the step. If a step size is chosen by the algorithm that is smaller than this, the path is deemed to have reached the minimum.


TYPE:

INTEGER


DEFAULT:

5000

Corresponding to 0.005 a.u.


OPTIONS:

$n$

User-defined. Tolerance = $n$/1000000 a.u.


RECOMMENDATION:

Use the default. Note that this option only controls the threshold for ending the RPATH job and does nothing to the intermediate steps of the calculation. A smaller value will provide reaction paths that end closer to the true minimum. Use of smaller values without adjusting RPATH_MAX_STEPSIZE, however, can lead to oscillations about the minimum.


RPA

Do an RPA calculation in addition to a CIS or TDDFT/TDA calculation.


TYPE:

LOGICAL/INTEGER


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not do an RPA calculation.

TRUE

Do an RPA calculation.

2

Do an RPA calculation without running CIS or TDDFT/TDA first.


RECOMMENDATION:

None


MAKE_CUBE_FILES

Requests generation of cube files for MOs, NTOs, or NBOs.


TYPE:

LOGICAL/STRING


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not generate cube files.

TRUE

Generate cube files for MOs and densities.

NTOS

Generate cube files for NTOs.

NBOS

Generate cube files for NBOs.


RECOMMENDATION:

None


SAPT_AO

Request an atomic-orbital version of SAPT.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Use the AO version of SAPT.

FALSE

Use the MO version of SAPT.


RECOMMENDATION:

Use the AO version, which exhibits ${O}(N^3)$ scaling without significant memory bottlenecks.


SAPT_BASIS

Controls the MO basis used for SAPT corrections.


TYPE:

STRING


DEFAULT:

MONOMER


OPTIONS:

MONOMER

Monomer-centered basis set (MCBS).

DIMER

Dimer-centered basis set (DCBS).

PROJECTED

Projected (pseudocanonicalized) basis set.


RECOMMENDATION:

The DCBS is more costly than the MCBS and can only be used with XPOL_MPOL_ORDER = GAS (i.e., it is not available for use with XPol). The PROJECTED choice is an efficient compromise that is available for use with XPol.


SAPT_CDFT_EDA

Request a SAPT/cDFT energy decomposition analysis


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Run a SAPT/cDFT calculation.

FALSE

Do not run SAPT/cDFT.


RECOMMENDATION:

None


SAPT_CPHF

Requests that the second-order corrections $E_\ensuremath{\mathrm{}}{ind}^{(2)}$ and $E_\ensuremath{\mathrm{}}{exch{-}ind}^{(2)}$ be replaced by their infinite-order “response” analogues, $E_\ensuremath{\mathrm{}}{ind,resp}^{(2)}$ and $E_\ensuremath{\mathrm{}}{exch{-}ind,resp}^{(2)}$.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Evaluate the response corrections and use $E_\ensuremath{\mathrm{}}{ind,resp}^{(2)}$ and $E_\ensuremath{\mathrm{}}{exch{-}ind,resp}^{(2)}$

FALSE

Omit these corrections and use $E_\ensuremath{\mathrm{}}{ind}^{(2)}$ and $E_\ensuremath{\mathrm{}}{exch{-}ind}^{(2)}$.


RECOMMENDATION:

Computing the response corrections requires solving CPHF equations for pair of monomers, which is somewhat expensive but may improve the accuracy when the monomers are polar.


SAPT_DISP_CORR

Request an empirical dispersion potential instead of calculating $E_{\text {disp}}^{(2)}$ and $E_{\text {exch-disp}}^{(2)}$ directly.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Use a dispersion force field.

FALSE

Calculate $E_{\text {disp}}^{(2)}$ and $E_{\text {exch-disp}}^{(2)}$.


RECOMMENDATION:

Dispersion potentials combined with AO-SAPT reduces the scaling from ${O}(N^5)$ to ${O}(N^3)$ with respect to monomer size, and second-order dispersion is not very accurate anyway.


SAPT_DISP_VERSION

Controls which dispersion potential is used for SAPT.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

1

Use the “first generation” (+aiD1) dispersion potential.[Lao and Herbert(2012b)]

2

Use the “second generation” (+aiD2) dispersion potential.[Lao and Herbert(2013)]

3

Use the “third generation” (+aiD3) dispersion potentials.[Lao and Herbert(2015)]


RECOMMENDATION:

Use +aiD3. The second- and third-generation versions were parameterized using ab initio dispersion data and afford accurate energy components, in addition to accurate total interaction energies. The third-generation version was parameterized using an expanded data set designed to reduce some large errors observed for $\pi $-stacked complexes using +aiD2.


SAPT_DSCF

Request the $\delta E_\ensuremath{\mathrm{}}{int}^{\rm HF}$ correction


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Evaluate this correction.

FALSE

Omit this correction.


RECOMMENDATION:

Evaluating the $\delta E_\ensuremath{\mathrm{}}{int}^{\rm HF}$ correction requires an SCF calculation on the entire (super)system. This corrections effectively yields a “Hartree-Fock plus dispersion” estimate of the interaction energy.


SAPT_EXCHANGE

Selects the type of first-order exchange that is used in a SAPT calculation.


TYPE:

STRING


DEFAULT:

S_SQUARED


OPTIONS:

S_SQUARED

Compute first order exchange in the single-exchange (“$S^2$") approximation.

S_INVERSE

Compute the exact first order exchange.


RECOMMENDATION:

The single-exchange approximation is expected to be adequate except possibly at very short intermolecular distances, and is somewhat faster to compute.


SAPT_ORDER

Selects the order in perturbation theory for a SAPT calculation.


TYPE:

STRING


DEFAULT:

SAPT2


OPTIONS:

SAPT1

First order SAPT.

SAPT2

Second order SAPT.

ELST

First-order Rayleigh-Schrödinger perturbation theory.

RSPT

Second-order Rayleigh-Schrödinger perturbation theory.


RECOMMENDATION:

SAPT2 is the most meaningful.


SAPT_PRINT

Controls level of printing in SAPT.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

$N$

Integer print level


RECOMMENDATION:

Larger values generate additional output.


SAPT

Requests a SAPT calculation.


TYPE:

BOOLEAN


DEFAULT:

FALSE


OPTIONS:

TRUE

Run a SAPT calculation.

FALSE

Do not run SAPT.


RECOMMENDATION:

If SAPT is set to TRUE, one should also specify XPOL = TRUE and XPOL_MPOL_ORDER = GAS.


SASF_RPA

Do an SA-SF-CIS/DFT calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not do an SA-SF-CIS/DFT calculation.

TRUE

Do an SA-SF-CIS/DFT calculation (requires ROHF ground state).


RECOMMENDATION:

None


SAVE_LAST_GPX

Save the last $\ensuremath{\mathbf{G}}[\ensuremath{\mathbf{P}}^{x}]$ when calculating dynamic polarizabilities in order to call the MOProp code in a second run, via MOPROP = 102.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

False

1

True


RECOMMENDATION:

None


SCALE_NUCLEAR_CHARGE

Scales charge of each nuclei by a certain value. The nuclear repulsion energy is calculated for the unscaled nuclear charges.


TYPE:

INTEGER


DEFAULT:

0

No scaling.


OPTIONS:

$n$

A total positive charge of (1+$n$/100)e is added to the molecule.


RECOMMENDATION:

NONE


SCFMI_FREEZE_SS

Keep the first several fragments unrelaxed in an SCFMI calculation.


TYPE:

INTEGER


DEFAULT:

0 (all fragments are active)


OPTIONS:

$n$

Freeze the first $n$ fragments.


RECOMMENDATION:

None


SCFMI_MODE

Determine whether generalized SCFMI is used and also the property of the working basis.


TYPE:

INTEGER


DEFAULT:

0 (“1" is used by basic “EDA2" calculations).


OPTIONS:

0

AO-block based SCFMI (the original definition of ALMOs).

1

Generalized SCFMI with basis vectors that are non-orthogonal between fragments.

2

Generalized SCFMI with basis vectors that are orthogonal between fragments.


RECOMMENDATION:

None


SCF_ALGORITHM

Algorithm used for converging the SCF.


TYPE:

STRING


DEFAULT:

DIIS

Pulay DIIS.


OPTIONS:

DIIS

Pulay DIIS.

DM

Direct minimizer.

DIIS_DM

Uses DIIS initially, switching to direct minimizer for later iterations

 

(See THRESH_DIIS_SWITCH, MAX_DIIS_CYCLES).

DIIS_GDM

Use DIIS and then later switch to geometric direct minimization

 

(See THRESH_DIIS_SWITCH, MAX_DIIS_CYCLES).

GDM

Geometric Direct Minimization.

RCA

Relaxed constraint algorithm

RCA_DIIS

Use RCA initially, switching to DIIS for later iterations (see

 

THRESH_RCA_SWITCH and MAX_RCA_CYCLES described

 

later in this chapter)

ROOTHAAN

Roothaan repeated diagonalization.


RECOMMENDATION:

Use DIIS unless performing a restricted open-shell calculation, in which case GDM is recommended. If DIIS fails to find a reasonable approximate solution in the initial iterations, RCA_DIIS is the recommended fallback option. If DIIS approaches the correct solution but fails to finally converge, DIIS_GDM is the recommended fallback.


SCF_CONVERGENCE

SCF is considered converged when the wave function error is less that $10^{-\mathrm{SCF\_ CONVERGENCE}}$. Adjust the value of THRESH at the same time. (Starting with Q-Chem 3.0, the DIIS error is measured by the maximum error rather than the RMS error as in earlier versions.)


TYPE:

INTEGER


DEFAULT:

5

For single point energy calculations.

8

For geometry optimizations and vibrational analysis.

8

For SSG calculations, see Chapter 6.


OPTIONS:

User-defined


RECOMMENDATION:

Tighter criteria for geometry optimization and vibration analysis. Larger values provide more significant figures, at greater computational cost.


SCF_FINAL_PRINT

Controls level of output from SCF procedure to Q-Chem output file at the end of the SCF.


TYPE:

INTEGER


DEFAULT:

0

No extra print out.


OPTIONS:

0

No extra print out.

1

Orbital energies and break-down of SCF energy.

2

Level 1 plus MOs and density matrices.

3

Level 2 plus Fock and density matrices.


RECOMMENDATION:

The break-down of energies is often useful (level 1).


SCF_GUESS_ALWAYS

Switch to force the regeneration of a new initial guess for each series of SCF iterations (for use in geometry optimization).


TYPE:

LOGICAL


DEFAULT:

False


OPTIONS:

False

Do not generate a new guess for each series of SCF iterations in an

 

optimization; use MOs from the previous SCF calculation for the guess,

 

if available.

True

Generate a new guess for each series of SCF iterations in a geometry

 

optimization.


RECOMMENDATION:

Use the default unless SCF convergence issues arise


SCF_GUESS_MIX

Controls mixing of LUMO and HOMO to break symmetry in the initial guess. For unrestricted jobs, the mixing is performed only for the alpha orbitals.


TYPE:

INTEGER


DEFAULT:

0 (FALSE)

Do not mix HOMO and LUMO in SCF guess.


OPTIONS:

0 (FALSE)

Do not mix HOMO and LUMO in SCF guess.

1 (TRUE)

Add 10% of LUMO to HOMO to break symmetry.

$n$

Add $n\times 10\% $ of LUMO to HOMO ($0<n<10$).


RECOMMENDATION:

When performing unrestricted calculations on molecules with an even number of electrons, it is often necessary to break alpha/beta symmetry in the initial guess with this option, or by specifying input for $occupied.


SCF_GUESS_PRINT

Controls printing of guess MOs, Fock and density matrices.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not print guesses.

SAD

 

1

Atomic density matrices and molecular matrix.

2

Level 1 plus density matrices.

CORE and GWH

 

1

No extra output.

2

Level 1 plus Fock and density matrices and, MO coefficients and

 

eigenvalues.

READ

 

1

No extra output

2

Level 1 plus density matrices, MO coefficients and eigenvalues.


RECOMMENDATION:

None


SCF_GUESS

Specifies the initial guess procedure to use for the SCF.


TYPE:

STRING


DEFAULT:

SAD

Superposition of atomic densities (available only with standard basis sets)

GWH

For ROHF where a set of orbitals are required.

FRAGMO

For a fragment MO calculation


OPTIONS:

CORE

Diagonalize core Hamiltonian

SAD

Superposition of atomic density

SADMO

Purified superposition of atomic densities (available only with standard basis sets)

GWH

Apply generalized Wolfsberg-Helmholtz approximation

READ

Read previous MOs from disk

FRAGMO

Superimposing converged fragment MOs


RECOMMENDATION:

SAD or SADMO guess for standard basis sets. For general basis sets, it is best to use the BASIS2 $rem. Alternatively, try the GWH or core Hamiltonian guess. For ROHF it can be useful to READ guesses from an SCF calculation on the corresponding cation or anion. Note that because the density is made spherical, this may favor an undesired state for atomic systems, especially transition metals. Use FRAGMO in a fragment MO calculation.


SCF_MINFIND_INCREASEFACTOR

Controls how the height of the penalty function changes when repeatedly trapped at the same solution


TYPE:

INTEGER


DEFAULT:

10100 meaning 1.01


OPTIONS:

$abcde$

corresponding to $a.bcde$


RECOMMENDATION:

If the algorithm converges to a solution which corresponds to a previously located solution, increase both the normalization N and the width lambda of the penalty function there. Then do a restart.


SCF_MINFIND_INITLAMBDA

Control the initial width of the penalty function.


TYPE:

INTEGER


DEFAULT:

02000 meaning 2.000


OPTIONS:

$abcde$

corresponding to $ab.cde$


RECOMMENDATION:

The initial inverse-width (i.e., the inverse-variance) of the Gaussian to place to fill solution’s well. Measured in electrons$^(-1)$. Increasing this will repeatedly converging on the same solution.


SCF_MINFIND_INITNORM

Control the initial height of the penalty function.


TYPE:

INTEGER


DEFAULT:

01000 meaning 1.000


OPTIONS:

$abcde$ corresponding to $ab.cde$


RECOMMENDATION:

The initial normalization of the Gaussian to place to fill a well. Measured in hartrees.


SCF_MINFIND_MIXENERGY

Specify the active energy range when doing Active mixing


TYPE:

INTEGER


DEFAULT:

00200 meaning 00.200


OPTIONS:

$abcde$ corresponding to $ab.cde$


RECOMMENDATION:

The standard deviation of the Gaussian distribution used to select the orbitals for mixing (centered on the Fermi level). Measured in Hartree. To find less-excited solutions, decrease this value


SCF_MINFIND_MIXMETHOD

Specify how to select orbitals for random mixing


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Random mixing: select from any orbital to any orbital.

1

Active mixing: select based on energy, decaying with distance from the Fermi level.

2

Active Alpha space mixing: select based on energy, decaying with distance from the

 

Fermi level only in the alpha space.


RECOMMENDATION:

Random mixing will often find very high energy solutions. If lower energy solutions are desired, use 1 or 2.


SCF_MINFIND_NRANDOMMIXES

Control how many random mixes to do to generate new orbitals


TYPE:

INTEGER


DEFAULT:

10


OPTIONS:

$n$

Perform $n$ random mixes.


RECOMMENDATION:

This is the number of occupied/virtual pairs to attempt to mix, per separate density (i.e., for unrestricted calculations both alpha and beta space will get this many rotations). If this is negative then only mix the highest 25% occupied and lowest 25% virtuals.


SCF_MINFIND_RANDOMMIXING

Control how to choose new orbitals after locating a solution


TYPE:

INTEGER


DEFAULT:

00200 meaning .02 radians


OPTIONS:

$abcde$ corresponding to $a.bcde$ radians


RECOMMENDATION:

After locating an SCF solution, the orbitals are mixed randomly to move to a new position in orbital space. For each occupied and virtual orbital pair picked at random and rotate between them by a random angle between 0 and this. If this is negative then use exactly this number, e.g., $-15708$ will almost exactly swap orbitals. Any number$<-15708$ will cause the orbitals to be swapped exactly.


SCF_MINFIND_READDISTTHRESH

The distance threshold at which to consider two solutions the same


TYPE:

INTEGER


DEFAULT:

00100 meaning 0.1


OPTIONS:

$abcde$ corresponding to $ab.cde$


RECOMMENDATION:

The threshold to regard a minimum as the same as a read in minimum. Measured in electrons. If two minima are closer together than this, reduce the threshold to distinguish them.


SCF_MINFIND_RESTARTSTEPS

Restart with new orbitals if no minima have been found within this many steps


TYPE:

INTEGER


DEFAULT:

300


OPTIONS:

$n$

Restart after $n$ steps.


RECOMMENDATION:

If the SCF calculation spends many steps not finding a solution, lowering this number may speed up solution-finding. If the system converges to solutions very slowly, then this number may need to be raised.


SCF_MINFIND_RUNCORR

Run post-SCF correlated methods on multiple SCF solutions


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

If this is set $>0$, then run correlation methods for all found SCF solutions.


RECOMMENDATION:

Post-HF correlation methods should function correctly with excited SCF solutions, but their convergence is often much more difficult owing to intruder states.


SCF_MINFIND_WELLTHRESH

Specify what SCF_MINFIND believes is the basin of a solution


TYPE:

INTEGER


DEFAULT:

5


OPTIONS:

$n$ for a threshold of $10^{-n}$


RECOMMENDATION:

When the DIIS error is less than $10^{-n}$, penalties are switched off to see whether it has converged to a new solution.


SCF_PRINT_FRGM

Controls the output of Q-Chem jobs on isolated fragments.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

The output is printed to the parent job output file.

FALSE

The output is not printed.


RECOMMENDATION:

Use TRUE if details about isolated fragments are important.


SCF_PRINT

Controls level of output from SCF procedure to Q-Chem output file.


TYPE:

INTEGER


DEFAULT:

0

Minimal, concise, useful and necessary output.


OPTIONS:

0

Minimal, concise, useful and necessary output.

1

Level 0 plus component breakdown of SCF electronic energy.

2

Level 1 plus density, Fock and MO matrices on each cycle.

3

Level 2 plus two-electron Fock matrix components (Coulomb, HF exchange

 

and DFT exchange-correlation matrices) on each cycle.


RECOMMENDATION:

Proceed with care; can result in extremely large output files at level 2 or higher. These levels are primarily for program debugging.


SCF_READMINIMA

Read in solutions from a previous SCF meta-dynamics calculation


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Read in $n$ previous solutions and attempt to locate them all.

$-n$

Read in $n$ previous solutions, but only attempt to locate solution $n$.


RECOMMENDATION:

This may not actually locate all solutions required and will probably locate others too. The SCF will also stop when the number of solutions specified in SCF_SAVEMINIMA are found. Solutions from other geometries may also be read in and used as starting orbitals. If a solution is found and matches one that is read in within SCF_MINFIND_READDISTTHRESH, its orbitals are saved in that position for any future calculations. The algorithm works by restarting from the orbitals and density of a the minimum it is attempting to find. After 10 failed restarts (defined by SCF_MINFIND_RESTARTSTEPS), it moves to another previous minimum and attempts to locate that instead. If there are no minima to find, the restart does random mixing (with 10 times the normal random mixing parameter).


SCF_SAVEMINIMA

Turn on SCF meta-dynamics and specify how many solutions to locate.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not use SCF meta-dynamics

$n$

Attempt to find $n$ distinct SCF solutions.


RECOMMENDATION:

Perform SCF Orbital meta-dynamics and attempt to locate $n$ different SCF solutions. Note that these may not all be minima. Many saddle points are often located. The last one located will be the one used in any post-SCF treatments. In systems where there are infinite point groups, this procedure cannot currently distinguish between spatial rotations of different densities, so will likely converge on these multiply.


SET_QUADRATIC

Determines whether to include full quadratic response contributions for TDDFT.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Include full quadratic response contributions for TDDFT.

FALSE

Use pseudo-wave function approach.


RECOMMENDATION:

The pseudo-wave function approach is usually accurate enough and is free of accidental singularities. Consult Refs. Zhang:2015a and Ou:2015 for additional guidance.


SET_STATE_DERIV

Sets the excited state index for analytical gradient calculation for geometry optimizations and vibrational analysis with SOS-CIS(D$_0$)


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Select the $n$th state.


RECOMMENDATION:

Check to see that the states do no change order during an optimization. For closed-shell systems, either CIS_SINGLETS or CIS_TRIPLETS must be set to false.


SFX_AMP_OCC_A

Defines a customer amplitude guess vector in SF-XCIS method.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

builds a guess amplitude with an $\alpha $-hole in the $n$th orbital (requires SFX_AMP_VIR_B).


RECOMMENDATION:

Only use when default guess is not satisfactory.


SFX_AMP_VIR_B

Defines a user-specified amplitude guess vector in SF-XCIS method.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

builds a guess amplitude with a $\beta $-particle in the $n$th orbital (requires SFX_AMP_OCC_A).


RECOMMENDATION:

Only use when default guess is not satisfactory.


SF_STATES

Controls the number of excited spin-flip states to calculate.


TYPE:

INTEGER


DEFAULT:

0

Do not perform a SF-ADC calculation


OPTIONS:

$n>0$

Number of states to calculate for each irrep or

$[n_1, n_2, ...]$

Compute $n_1$ states for the first irrep, $n_2$ states for the second irrep, ...


RECOMMENDATION:

Use this variable to define the number of excited states in the case of a spin-flip calculation. SF-ADC is available for ADC(2)-s, ADC(2)-x and ADC(3).


SKIP_CHARGE_SELF_INTERACT

Ignores the electrostatic interactions among external charges in a QM/MM calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

No electrostatic interactions among external charges.

FALSE

Computes the electrostatic interactions among external charges.


RECOMMENDATION:

None


SKIP_CIS_RPA

Skips the solution of the CIS, RPA, TDA or TDDFT equations for wave function analysis.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE / FALSE


RECOMMENDATION:

Set to true to speed up the generation of plot data if the same calculation has been run previously with the scratch files saved.


SOLVENT_METHOD

Sets the preferred solvent method.


TYPE:

STRING


DEFAULT:

0


OPTIONS:

0

Do not use a solvation model.

ONSAGER

Use the Kirkwood-Onsager model (Section 12.2.1).

PCM

Use an apparent surface charge, polarizable continuum model

 

(Section 12.2.2).

ISOSVP

Use the isodensity implementation of the SS(V)PE model

 

(Section 12.2.5).

COSMO

Use COSMO (similar to C-PCM but with an outlying charge

 

correction;[Klamt and Jonas(1996), Baldridge and Klamt(1997)] see Section 12.2.7).

SM8

Use version 8 of the Cramer-Truhlar SM$x$ model (Section 12.2.8.1).

SM12

Use version 12 of the SM$x$ model (Section 12.2.8.2).

SMD

Use SMD (Section 12.2.8.3).

CHEM_SOL

Use the Langevin Dipoles model (Section 12.2.9).


RECOMMENDATION:

Consult the literature. PCM is a collective name for a family of models and additional input options may be required in this case, in order to fully specify the model. (See Section 12.2.2.) Several versions of SM12 are available as well, as discussed in Section 12.2.8.2.


SOLVE_PEQ

Perform a solvation free energy calculation on a Cartesian grid using Poisson equation boundary conditions.


TYPE:

STRING


DEFAULT:

False


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

None.


SOS_FACTOR

Sets the scaling parameter $c_ T$


TYPE:

INTEGER


DEFAULT:

1300000

corresponding to 1.30


OPTIONS:

$n$

$c_ T = n / 1000000$


RECOMMENDATION:

Use the default


SOS_UFACTOR

Sets the scaling parameter $c_ U$


TYPE:

INTEGER


DEFAULT:

151

For SOS-CIS(D), corresponding to 1.51

140

For SOS-CIS(D$_0$), corresponding to 1.40


OPTIONS:

$n$

$c_ U = n / 100$


RECOMMENDATION:

Use the default


SPIN_FLIP_XCIS

Do a SF-XCIS calculation.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not do an SF-XCIS calculation.

TRUE

Do an SF-XCIS calculation (requires ROHF triplet ground state).


RECOMMENDATION:

None


SPIN_FLIP

Selects whether to perform a standard excited state calculation, or a spin-flip calculation. Spin multiplicity should be set to 3 for systems with an even number of electrons, and 4 for systems with an odd number of electrons.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

None


SRC_DFT

Selects form of the short-range corrected functional.


TYPE:

INTEGER


DEFAULT:

No default


OPTIONS:

1

SRC1 functional.

2

SRC2 functional.


RECOMMENDATION:

None


SSG

Controls the calculation of the SSG wave function.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

Do not compute the SSG wave function

1

Do compute the SSG wave function


RECOMMENDATION:

See also the UNRESTRICTED and DIIS_SUBSPACE_SIZE $rem variables.


SSS_FACTOR

Controls the strength of the same-spin component of PT2 correlation energy.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

$n$

Corresponding to $c_\ensuremath{\mathrm{}}{ss} = n/10^6$ in Eq. (5.60).


RECOMMENDATION:

NONE


STABILITY_ANALYSIS

Performs stability analysis for a HF or DFT solution.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform stability analysis.

FALSE

Do not perform stability analysis.


RECOMMENDATION:

Set to TRUE when a HF or DFT solution is suspected to be unstable.


STATE_ANALYSIS

Controls the analysis and export of excited state densities and orbitals (see 11.2.6 for details).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

TRUE

Perform excited state analyses.

FALSE

No excited state analyses or export will be performed.


RECOMMENDATION:

Set to TRUE, if detailed analysis of the excited states is required or if density or orbital plots are needed.


STATE_FOLLOW

Turns on state following.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not use state-following.

TRUE

Use state-following.


RECOMMENDATION:

None.


STS_ACCEPTOR

Define the acceptor molecular fragment.


TYPE:

STRING


DEFAULT:

0

No acceptor fragment is defined.


OPTIONS:

$i$-$j$

Acceptor fragment is in the $i$th atom to the $j$th atom.


RECOMMENDATION:

Note no space between the hyphen and the numbers $i$ and $j$.


STS_DONOR

Define the donor fragment.


TYPE:

STRING


DEFAULT:

0

No donor fragment is defined.


OPTIONS:

$i$-$j$

Donor fragment is in the $i$th atom to the $j$th atom.


RECOMMENDATION:

Note no space between the hyphen and the numbers $i$ and $j$.


STS_FCD

Control the calculation of FCD for ET couplings.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform an FCD calculation.

TRUE

Include an FCD calculation.


RECOMMENDATION:

None


STS_FED

Control the calculation of FED for EET couplings.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform a FED calculation.

TRUE

Include a FED calculation.


RECOMMENDATION:

None


STS_FSD

Control the calculation of FSD for EET couplings.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform a FSD calculation.

TRUE

Include a FSD calculation.


RECOMMENDATION:

For RCIS triplets, FSD and FED are equivalent. FSD will be automatically switched off and perform a FED calculation.


STS_GMH

Control the calculation of GMH for ET couplings.


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform a GMH calculation.

TRUE

Include a GMH calculation.


RECOMMENDATION:

When set to true computes Mulliken-Hush electronic couplings. It yields the generalized Mulliken-Hush couplings as well as the transition dipole moments for each pair of excited states and for each excited state with the ground state.


STS_MOM

Control calculation of the transition moments between excited states in the CIS and TDDFT calculations (including SF variants).


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not calculate state-to-state transition moments.

TRUE

Do calculate state-to-state transition moments.


RECOMMENDATION:

When set to true requests the state-to-state dipole transition moments for all pairs of excited states and for each excited state with the ground state.


SVP_CAVITY_CONV

Determines the convergence value of the iterative isodensity cavity procedure.


TYPE:

INTEGER


DEFAULT:

10


OPTIONS:

$n$

Convergence threshold set to $10^{-n}$.


RECOMMENDATION:

The default value unless convergence problems arise.


SVP_CHARGE_CONV

Determines the convergence value for the charges on the cavity. When the change in charges fall below this value, if the electron density is converged, then the calculation is considered converged.


TYPE:

INTEGER


DEFAULT:

7


OPTIONS:

$n$

Convergence threshold set to $10^{-n}$.


RECOMMENDATION:

The default value unless convergence problems arise.


SVP_GUESS

Specifies how and if the solvation module will use a given guess for the charges and cavity points.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

No guessing.

1

Read a guess from a previous Q-Chem solvation computation.

2

Use a guess specified by the $svpirf section from the input


RECOMMENDATION:

It is helpful to also set SCF_GUESS to READ when using a guess from a previous Q-Chem run.


SVP_MEMORY

Specifies the amount of memory for use by the solvation module.


TYPE:

INTEGER


DEFAULT:

125


OPTIONS:

$n$ corresponds to the amount of memory in Mb.


RECOMMENDATION:

The default should be fine for medium size molecules with the default Lebedev grid, only increase if needed.


SVP_PATH

Specifies whether to run a gas phase computation prior to performing the solvation procedure.


TYPE:

INTEGER


DEFAULT:

0


OPTIONS:

0

runs a gas-phase calculation and after

 

convergence runs the SS(V)PE computation.

1

does not run a gas-phase calculation.


RECOMMENDATION:

Running the gas-phase calculation provides a good guess to start the solvation stage and provides a more complete set of solvated properties.


SYMMETRY_DECOMPOSITION

Determines symmetry decompositions to calculate.


TYPE:

INTEGER


DEFAULT:

1


OPTIONS:

0

No symmetry decomposition.

1

Calculate MO eigenvalues and symmetry (if available).

2

Perform symmetry decomposition of kinetic energy and nuclear attraction

 

matrices.


RECOMMENDATION:

None


SYMMETRY

Controls the efficiency through the use of point group symmetry for calculating integrals.


TYPE:

LOGICAL


DEFAULT:

TRUE

Use symmetry for computing integrals.


OPTIONS:

TRUE

Use symmetry when available.

FALSE

Do not use symmetry. This is always the case for RIMP2 jobs


RECOMMENDATION:

Use the default unless benchmarking. Note that symmetry usage is disabled for RIMP2, FFT, and QM/MM jobs.


SYM_IGNORE

Controls whether or not Q-Chem determines the point group of the molecule and reorients the molecule to the standard orientation.


TYPE:

LOGICAL


DEFAULT:

FALSE

Do determine the point group (disabled for RIMP2 jobs).


OPTIONS:

TRUE/FALSE


RECOMMENDATION:

Use the default unless you do not want the molecule to be reoriented. Note that symmetry usage is disabled for RIMP2 jobs.


SYM_TOL

Controls the tolerance for determining point group symmetry. Differences in atom locations less than $10^{-\mathrm{SYM\_ TOL}}$ are treated as zero.


TYPE:

INTEGER


DEFAULT:

5

Corresponding to $10^{-5}$.


OPTIONS:

User defined.


RECOMMENDATION:

Use the default unless the molecule has high symmetry which is not being correctly identified. Note that relaxing this tolerance too much may introduce errors into the calculation.


TAO_DFT_THETA_NDP

Controls the value of the fictitious temperature $\theta $ in TAO-DFT.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS:

$n$

$\theta =m\times 10^{-n}$ (hartrees), where $m$ is the value of TAO_DFT_THETA


RECOMMENDATION:

NONE


TAO_DFT_THETA

Controls the value of the fictitious temperature $\theta $ in TAO-DFT.


TYPE:

INTEGER


DEFAULT:

7


OPTIONS:

$m$

$\theta =m\times 10^{-n}$ (hartrees), where $n$ is the value of TAO_DFT_THETA_NDP


RECOMMENDATION:

NONE


TAO_DFT

Controls whether to use TAO-DFT.


TYPE:

Boolean


DEFAULT:

false


OPTIONS:

false

Do not use TAO-DFT

true

Use TAO-DFT


RECOMMENDATION:

NONE


TDDFT_MI

Perform an TDDFT(MI) calculation


TYPE:

LOGICAL


DEFAULT:

FALSE


OPTIONS:

FALSE

Do not perform an TDDFT(MI) calculation

TRUE

Perform an TDDFT(MI) calculation


RECOMMENDATION:

False


THRESH_DIIS_SWITCH

The threshold for switching between DIIS extrapolation and direct minimization of the SCF energy is $10^{-\mbox{{\small THRESH\_ DIIS\_ SWITCH}}}$ when SCF_ALGORITHM is DIIS_GDM or DIIS_DM. See also MAX_DIIS_CYCLES


TYPE:

INTEGER


DEFAULT:

2


OPTIONS:

User-defined.


RECOMMENDATION:

None


THRESH_RCA_SWITCH

The threshold for switching between RCA and DIIS when SCF_ALGORITHM is RCA_DIIS.


TYPE:

INTEGER


DEFAULT:

3


OPTIONS: