Q-Chem
Q-Chem is a modern ab initio, electronic structure program package, capable of performing first principles calculations on the ground and excited states of molecules.
Program Features
Linear scaling methods for Hartree-Fock and DFT calculations
- CFMM for Coulomb interactions (energies and gradients)
- LinK for exchange interactions (energies and gradients)
- Linear scaling exchange-correlation quadrature
Local, Gradient-Corrected and Hybrid DFT functionals
- Slater, Becke, GGA91 and Gill '96 exchange functionals
- VWN, PZ81, Wigner, Perdew86, LYP and GGA91 correlation functionals
- EDF1 exchange-correlation functional
- B3LYP, B3P and user-definable hybrids
- Analytical gradients and analytical frequencies
Post-Hartree-Fock wavefunction-based electron correlation methods
- Efficient semidirect MP2 energies and gradients
- Local MP2 for energies using the TRIM and DIM models
- MP3, MP4, QCISD, CCSD energies
- OD and QCCD energies and analytical gradients
- QCISD(T), CCSD(T) and OD(T) energies
- CCSD(2) and OD(2) energies
- active space coupled cluster methods: VOD, VQCCD, VOD(2)
Extensive excited state capabilities
- CIS energies, analytical gradients and analytical
- frequencies
- CIS(D) energies
- Time-dependent density functional theory energies (TDDFT)
- Coupled cluster excited state energies (OD, and VOD)
Evaluation and visualization of molecular properties
- Langevin dipoles solvation model
- Evaluate densities, electrostatic potentials, orbitals over cubes for plotting
- Natural Bond Orbital (NBO) analysis
- Attachment-detachment densities for excited states via CIS, TDDFT
- Vibrational analysis after evaluation of the nuclear coordinate Hessian
High performance geometry and transition structure optimization
- Optimizes in Cartesian, Z-matrix or delocalized internal coordinates
- Impose bond angle, dihedral angle (torsion) or out-of-plane bend constraints
- Freezes atoms in Cartesian coordinates
- Constraints do not need to be satisfied in the starting structure
- Geometry optimization in the presence of fixed point charges
Running Q-Chem:
k2 - You will need to add the following lines to your .tcshrc file:
setenv QC /usr/local/lms/qchem/qchem2.02
setenv QCAUX $QC/aux
setenv QCSCRATCH /tmp/$LOGNAME
setenv QCPLATFORM SGI_IRIX64
if (-e $QC/bin/qchem.setup) source $QC/bin/qchem.setup
For information on how to obtain an account on k2.tamu.edu please visit the Supercomputing web site
http://sc.tamu.edu/
