GAMESS is a program for ab initio molecular quantum chemistry. Briefly, GAMESS
can compute SCF wavefunctions ranging from RHF, ROHF, UHF, GVB, and MCSCF.
Correlation corrections to these SCF wavefunctions include Configuration
Interaction, second order perturbation Theory, and Coupled-Cluster approaches,
as well as the Density Functional Theory approximation. Excited states can be
computed by CI, EOM, or TD-DFT procedures. Nuclear gradients are available, for
automatic geometry optimization, transition state searches, or reaction path
following. Computation of the energy hessian permits prediction of vibrational
frequencies, with IR or Raman intensities. Solvent effects may be modeled by the
discrete Effective Fragment potentials, or continuum models such as the
Polarizable Continuum Model. Numerous relativistic computations are available,
including infinite order two component scalar relativity corrections, with
various spin-orbit coupling options. The Fragment Molecular Orbital method
permits use of many of these sophisticated treatments to be used on very large
systems, by dividing the computation into small fragments. Nuclear wavefunctions
can also be computed, in VSCF, or with explicit treatment of nuclear orbitals by
the NEO code.

This is the 'US' fork of GAMES. 'UK' fork also exists.

WWW: https://www.msg.chem.iastate.edu/gamess/