Official Resources
- Homepage: https://www.msg.chem.iastate.edu/gamess/
- Source Repository: Source-available (not open-source); distributed from Iowa State University
- Documentation: https://www.msg.chem.iastate.edu/GAMESS/GAMESS_Manual/docs-intro.txt
- License: Proprietary (free for academic and industrial use with site license)
Overview
GAMESS (General Atomic and Molecular Electronic Structure System), also known as GAMESS-US, is a general-purpose ab initio quantum chemistry package maintained by the Gordon Research Group at Iowa State University. The original code began on October 1, 1977 as a National Resources for Computations in Chemistry project. In 1981, the code base split into GAMESS (US) and GAMESS (UK) variants, which now differ significantly.
GAMESS-US performs a wide range of quantum chemical computations including Hartree-Fock, density functional theory, generalized valence bond, and multi-configurational self-consistent field methods. Correlation corrections can be estimated via configuration interaction, MP2, coupled cluster, and equation-of-motion coupled cluster methodologies. The software also supports semi-empirical methods (MNDO, AM1, PM3), QM/MM calculations, and solvent effects. GAMESS-US runs on nearly all computer systems from large parallel systems to desktops and laptops, and its fragmentation methods can scale to as many as 260,000 cores.
Scientific domain: Quantum chemistry, computational chemistry
Target user community: Computational chemists in academia and industry
Theoretical Methods
- RHF, UHF, ROHF, REKS, GVB, and MCSCF self-consistent field wavefunctions
- DFT with various exchange-correlation functionals
- Configuration interaction (CI)
- Møller-Plesset perturbation theory (MP2)
- Coupled cluster (CC) and EOM-CC methodologies
- Valence bond (VB) theory
- Semi-empirical methods (MNDO, AM1, PM3)
- QM/MM with effective fragment potentials
- Solvent models (PCM)
- Relativistic corrections (Douglas-Kroll)
- Resolution-of-the-Identity (RI) approximated methods
- Fragmentation methods for large systems
Capabilities (CRITICAL)
- Comprehensive ab initio quantum chemistry suite
- Hartree-Fock, DFT, MCSCF, CI, MP2, CC, and EOM-CC methods
- Semi-empirical calculations (MNDO, AM1, PM3)
- QM/MM with discrete effective fragment potentials
- Continuum solvent models (PCM)
- Relativistic corrections including third-order Douglas-Kroll
- RI-approximated MP2 and CCSD(T)
- Fragmentation methods scaling to 260,000 cores
- Runs on Linux, macOS, Windows
- GamessQ batch queue manager for desktop use
- Free site license for academic and industrial users
Inputs & Outputs
Input formats:
- GAMESS input files with $SYSTEM, $BASIS, $CONTRL keyblocks
- Basis set specifications
- Geometry input (Z-matrix or Cartesian)
Output data types:
- Total energies and gradients
- Molecular orbitals and eigenvalues
- Excited state energies and transition moments
- Vibrational frequencies and IR intensities
- NMR properties
- Population analysis
Interfaces & Ecosystem
- Programming language: Fortran, C
- Parallel computing: MPI, scaling to 260,000 cores via fragmentation methods
- Platforms: Linux, macOS, Windows, HPC clusters
- Graphics: Built-in visualization tools, MacMolPlt, wxMacMolPlt
- Workflow tools: GamessQ for desktop batch management
Limitations & Known Constraints
- Source-available but not truly open-source (license restrictions)
- Input format uses dated keyblock syntax
- Some advanced methods require significant computational resources
- Documentation can be technical and overwhelming for new users
Performance Characteristics
- Scales to 260,000 cores with fragmentation methods
- RI approximation reduces computational cost for MP2 and CCSD(T)
- Efficient for both small molecule high-accuracy and large molecule low-accuracy calculations
- Parallel execution on dedicated HPC facilities
Comparison with Other Codes
- vs Gaussian: Both are comprehensive QC suites; GAMESS-US is free while Gaussian is commercial
- vs NWChem: NWChem is truly open-source (ECL); GAMESS-US has license restrictions but is free to use
- vs ORCA: ORCA has modern input and extensive DFT features; GAMESS-US has longer history and broader method range
- vs GAMESS-UK: Separate development branches since 1981 with significantly different features
Best Practices
- Use fragmentation methods for very large molecular species
- Leverage RI approximation for MP2 and CCSD(T) calculations
- Use GamessQ for desktop batch management
- Consult the comprehensive documentation for method-specific settings
- Use effective fragment potentials for QM/MM calculations
Verification & Sources
Primary sources:
- Official website: https://www.msg.chem.iastate.edu/gamess/
- M.W. Schmidt et al., J. Comput. Chem. 14, 1347-1363 (1993)
- M.S. Gordon et al., J. Chem. Phys. 113, 4049 (2000)
Confidence: VERIFIED - Official website and documentation confirmed accessible