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| MOPAC | |
|---|---|
| Name | MOPAC |
| Developer | J. J. P. Stewart; Stewart Computational Chemistry |
| Released | 1970s |
| Latest release | Various (MOPAC2016, MOPAC2012, earlier versions) |
| Programming language | FORTRAN |
| Operating system | Unix, Linux, Windows, macOS |
| Genre | Computational chemistry, Quantum chemistry |
| License | Proprietary, Academic licenses |
MOPAC. MOPAC is a semiempirical quantum chemistry software package widely used for molecular electronic structure calculations and geometry optimization. It provides parametrized methods for approximate solutions to the Schrödinger equation, enabling studies of molecular properties, reaction pathways, and spectroscopy across chemical, biochemical, and materials contexts. The package has influenced computational workflows in laboratories and industry alongside programs such as Gaussian (software), GAMESS (US), NWChem, ORCA (chemistry), and Spartan (software).
MOPAC implements semiempirical methods including MNDO, AM1, PM3, PM6, and PM7, operating within the NDDO framework that complements ab initio programs like Molpro, Psi4, Q-Chem, CFOUR, and ACES II. The package is often used with visualization tools such as GaussView, Avogadro (software), VMD (software), Jmol, and Chimera (molecular) for interpreting results in studies relating to Nobel Prize in Chemistry, Royal Society of Chemistry-published work, and projects at institutions like MIT, Stanford University, Harvard University, University of California, Berkeley, and ETH Zurich. MOPAC connects to force field programs and molecular dynamics engines including LAMMPS, AMBER, GROMACS, CHARMM, and NAMD (software).
Development began in the 1970s under John Pople’s legacy era and was advanced by James J. P. Stewart, with milestones paralleling releases of Gaussian (software), the founding of GAMESS (US), and growth of computational chemistry clusters at Los Alamos National Laboratory, Argonne National Laboratory, Bell Labs, and IBM Research. Key institutional users included SRI International, Sandia National Laboratories, Lawrence Livermore National Laboratory, and academic groups at Caltech, University of Oxford, University of Cambridge, and Imperial College London. Over time, improvements paralleled algorithmic advances in programs such as Fast multipole method, integration developments like those in BLAS and LAPACK, and grid computing initiatives such as TeraGrid and XSEDE.
MOPAC's theoretical foundation rests on semiempirical NDDO-based parameterizations including MNDO, AM1, PM3, PM6, and PM7, which are alternatives to ab initio approaches seen in Hartree–Fock method, Density Functional Theory, and post-Hartree–Fock methods implemented in Gaussian (software), Molpro, CFOUR, and ORCA (chemistry). Its treatment of electron correlation and parametrization strategies intersect with concepts explored by researchers awarded the Nobel Prize in Chemistry and institutions like Max Planck Society and CNRS. Parameter sets were derived using data sources from experimental groups at National Institute of Standards and Technology, Brookhaven National Laboratory, Centre National de la Recherche Scientifique, and databases maintained by Cambridge Crystallographic Data Centre. The mathematical underpinnings relate to techniques used in Monte Carlo method, Molecular orbital theory, and concepts such as Koopmans' theorem as employed in Hartree–Fock method studies.
MOPAC is implemented primarily in FORTRAN and distributed as command-line executables compatible with Unix, Linux, Windows, and macOS, similar to legacy scientific codes like Gaussian (software), NWChem, and GAMESS (US). Features include geometry optimization, transition state searches, vibrational frequency analysis, reaction path following, and population analyses comparable to outputs in ORCA (chemistry) and Psi4. Interfaces and wrappers have been developed for workflow systems such as Open Babel, ASE (Atomic Simulation Environment), AutoDock, PyMOL, and KNIME. Parallelization exploits MPI libraries used in OpenMPI and MPICH environments on hardware from vendors like Intel Corporation, AMD (company), NVIDIA, and HPC centers such as Oak Ridge National Laboratory and European Centre for Medium-Range Weather Forecasts clusters.
MOPAC is applied in organic chemistry, medicinal chemistry, materials science, and enzymology for rapid evaluations of heats of formation, dipole moments, conformational analyses, and reaction energetics. It has been cited in studies connected to Pfizer, Merck & Co., AstraZeneca, and academic projects at Johns Hopkins University, University of Tokyo, Peking University, and University of Toronto. Applications overlap with cheminformatics platforms like RDKit and ChemAxon workflows and support high-throughput virtual screening pipelines analogous to those used at DrugBank, PubChem, and ZINC (database). MOPAC facilitates interpretation of spectroscopic data from facilities such as European Synchrotron Radiation Facility, Diamond Light Source, Advanced Photon Source, and complements experimental techniques practiced at Brookhaven National Laboratory and SLAC National Accelerator Laboratory.
Benchmarking of MOPAC parameter sets has been conducted against high-level calculations from Coupled cluster, CCSD(T), and DFT results from B3LYP and PBE0 functionals as implemented in Gaussian (software), ORCA (chemistry), and Psi4. Validation studies appear in journals associated with American Chemical Society, Nature Publishing Group, Royal Society of Chemistry, and Springer Nature, and are performed by groups at University of California, Los Angeles, Princeton University, and Yale University. Performance evaluations examine trade-offs between speed and accuracy relative to ab initio packages, and involve test suites from GMTKN55-like initiatives and datasets compiled by NIST Chemistry WebBook contributors.
MOPAC is distributed under proprietary and academic licensing models managed by Stewart Computational Chemistry and related distributors, with releases such as MOPAC2012 and MOPAC2016 provided to universities and companies under negotiated terms similar to licenses for Gaussian (software) and commercial tools sold by Schrödinger (company). Source code availability and redistribution policies differ from open-source projects like GAMESS (US), NWChem, and Psi4, while community support and training occur at conferences organized by American Chemical Society divisions, Gordon Research Conferences, International Conference on Computational Chemistry, and workshops at European Molecular Biology Laboratory.
Category:Computational chemistry software