GAMESS (US)


General Atomic and Molecular Electronic Structure System is computer software for computational chemistry program. The original code started on October 1, 1977 as a National Resources for Computations in Chemistry project. In 1981, the code base split into GAMESS and GAMESS variants, which now differ significantly. GAMESS is maintained by the members of the Gordon Research Group at Iowa State University. GAMESS source code is available as source-available freeware, but is not open-source software, due to license restrictions.

Abilities

SCFTYP=RHFROHFUHFGVBMCSCF
Energy
Analytic gradient
Numerical Hessian
Analytic Hessian
MP2 energy
MP2 gradient
CI energy
CI gradient
CC energy
EOM energy
DFT energy
DFT gradient
TD-DFT energy
TDDFT gradient
MOPAC energy
MOPAC gradient

GAMESS can perform several general computational chemistry calculations, including Hartree–Fock method, density functional theory, generalized valence bond, and multi-configurational self-consistent field. Correlation corrections after these SCF calculations can be estimated by configuration interaction, second order Møller–Plesset perturbation theory, and coupled cluster theory. Solvent effect can be considered using quantum mechanics and molecular mechanics through discrete effective fragment potentials or continuum models. Relativistic corrections can be calculated, including third order Douglas-Kroll scalar terms.
While the program does not directly perform molecular mechanics, it can do mixed quantum mechanics and molecular mechanics calculations through effective fragment potentials or through an interface with the Tinker code. The fragment molecular orbital method can be used to treat large systems, by dividing them into fragments.
It can also be interfaced with the valence bond VB2000 and XMVB programs and the Natural Bond Orbital population analysis program.
The input files use a keyword based scheme. For example, $CONTRL SCFTYP=ROHF MAXIT=30 $END, which specifies that the SCF part of the code should do a restricted open-shell Hartree–Fock calculation and quit if the result does not converge in 30 iterations. The output is in an English language text file.