New Features in Q-Chem 3.2
(click here for supported platforms)
- Several new DFT functional options:
- Solvation models:
- SM8 model (energy and analytical gradient) for water and organic solvents
- Updates to Onsager reaction-field model
- Intermolecular interaction analysis:
- SCF with absolutely localized molecular orbitals for molecule interaction (SCF-MI)
- Roothaan-step (RS) correction following SCF-MI
- Energy decomposition analysis (EDA)
- Complementary occupied-virtual pair (COVP) analysis for charge transfer
- Automated basis-set superposition error (BSSE) calculation
- Electron transfer analysis
- Relaxed constraint algorithm (RCA) for converging SCF
- G3Large basis set for transition metals
- New MP2 options:
- Dual-basis RIMP2 energy and analytical gradient
- O2 energy and gradient
- New wavefunction-based methods for efficiently calculating excited state properties:
- SOS-CIS(D) energy for excited states
- SOS-CIS(D0) energy and gradient for excited states
- Coupled-cluster methods:
- IP-CISD energy and gradient
- EOM-IP-CCSD energy and gradient
- OpenMP for parallel coupled-cluster calculations
- QM/MM methods:
- QM/MM full hessian evaluation
- QM/MM mobile-block hessian (MBH) evaluation
- Description for MM atoms with Gaussian-delocalized charge
- Partial Hessian method for vibrational analysis
- Wavefunction analysis tools:
- Improved algorithms for computing localized orbitals
- Distributed multipole analysis
- Analytical Wigner intracule
New Features in Q-Chem 3.1
- Several new DFT functional options:
- The nonempirical GGA functional PBE
- M05 and M06 suites of meta-GGA functionals for more accurate predictions of various types of reactions and systems
- The nonempirical GGA functional PBE
- Faster correlated excited state method: RI-CIS(D)
- Potential energy surface crossing minimization with EOM-CCSD
- Dyson orbitals for ionization from the ground and excited states within CCSD and EOM-CCSD methods
New Features of Q-Chem 3.0
Q-Chem 3.0, a new major release, is a comprehensive ab initio
quantum chemistry package -- the ultimate quantum solution to problems
of all sizes. It is available fully-integrated as the back end of Spartan '06
and stand-alone (LINUX, Mac OS and other
UNIX platforms).
Q-Chem 3.0: Making a Difference
| Key Features | Innovation | Benefit |
| NMR Chemical Shifts | 1st Linear-scaling NMR | Feasible for hundreds of atoms |
| Fast DFT Calculations | New FTC and DFT methods | Up to 3 times faster |
| Fast MP2 Calculations | RI-MP2 (with gradients) RI-TRIM local MP2 | 3 to 10 times faster |
| Scaled MP2 Schemes | New SOS-MP2, MOS-MP2 schemes with RI, gradients | More accurate and faster |
| Coupled Cluster Methods | EOM-(EE, IP, EA, SF)-CCSD methods with gradients and properties | Robust and efficient treatment of open-shell and electronically excited species |
| Valence Correlation Models | SSG, PP, IP, RP methods with gradients | Inexpensive alternative to GVB/CASSCF-type models |
| QM/MM Hybrid Methods | ONIOM Energy, Gradient, Frequency | Suitable for huge structures |
| Anharmonic Frequencies | New TOSH Model | Direct prediction of IR peaks |
| Continuum Solvation Model | SS(V)PE Electronic Model | Improved accuracy for ions |
| Parallel DFT/HF | Energies, gradients and frequencies (with distributed memory) | Scalable to many CPUs |
| Dual Basis Methods | HF, DFT, MP2 energies | About 10 times faster for large basis sets |
| Transition Structure Finder | Growing String Method | Improved search Tool |
| Direct Dynamics | Extended Lagrangian and Born-Oppenheimer |
Enables trajectory studies |
| Graphic User Interface | WebMO on distribution CD | Basic builder and viewer |
For a complete list of features please see Q-Chem User's Guide
Q-Chem in Action
> Fast DFT on Linux Clusters
It takes Q-Chem 8 minutes to do an energy and gradient calculation for this 103-atom taxol molecule at BLYP/6-311G (df,pd) level with 2000 basis functions on an 8-cpu opteron cluster.
> MP2 at HF Speed
Highly efficient resolution-of-the-identity (RI) algorithms make
medium & large basis MP2 calculations much more efficient, as
shown in this example of computing the relative conformational energy
of alanine
tetrapeptide (there are 27 low-lying structures!).
> Linear-Scaling NMR Calculation
This diagram and table show the convergence of NMR shifts of the depicted object (N-methyl nicotinamide surrounded by hundreds of water molecules) versus the number of surrounding water molecules. They represent the largest NMR calculations, with up to 9000 basis functions at HF/6-31G** level.
> A New Finding
Q-Chem’s unique EOM-SF-CCSD method, which is capable of efficiently describing multiple states of di- and tri-radicals, was used to discover the first example of an organic molecule with an open-shell doublet ground state. These three unpaired electrons are coupled antiferromagnetically in the DMX triradical.