Q-Chem 4.4 User’s Manual

12.6 Job Control for Locally-Projected SCF Methods

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.


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.


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.


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_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.


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_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_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_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.


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_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 $n$ ngstroms

 

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.