Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of molecules, groups of molecules, and solids. It is essential because, apart from relatively recent results concerning the hydrogen molecular ion, the quantum many-body problem cannot be solved analytically, much less in closed form. While computational results normally complement the information obtained by chemical experiments, it can in some cases predict hitherto unobserved chemical phenomena. It is widely used in the design of new drugs and materials.
Quantum chemistry, also called molecular quantum mechanics, is a branch of physical chemistry focused on the application of quantum mechanics to chemical systems, particularly towards the quantum-mechanical calculation of electronic contributions to physical and chemical properties of molecules, materials, and solutions at the atomic level. These calculations include systematically applied approximations intended to make calculations computationally feasible while still capturing as much information about important contributions to the computed wave functions as well as to observable properties such as structures, spectra, and thermodynamic properties. Quantum chemistry is also concerned with the computation of quantum effects on molecular dynamics and chemical kinetics.
Q-Chem is a general-purpose electronic structure package featuring a variety of established and new methods implemented using innovative algorithms that enable fast calculations of large systems on various computer architectures, from laptops and regular lab workstations to midsize clusters and HPCC, using density functional and wave-function based approaches. It offers an integrated graphical interface and input generator; a large selection of functionals and correlation methods, including methods for electronically excited states and open-shell systems; solvation models; and wave-function analysis tools. In addition to serving the computational chemistry community, Q-Chem also provides a versatile code development platform.
MPQC is an ab initio computational chemistry software program. Three features distinguish it from other quantum chemistry programs such as Gaussian and GAMESS: it is open-source, has an object-oriented design, and is created from the beginning as a parallel processing program. It is available in Ubuntu and Debian.
Molden is a general molecular and electronic structure processing program.
MNDO, or Modified Neglect of Diatomic Overlap is a semi-empirical method for the quantum calculation of molecular electronic structure in computational chemistry. It is based on the Neglect of Diatomic Differential Overlap integral approximation. Similarly, this method replaced the earlier MINDO method. It is part of the MOPAC program and was developed in the group of Michael Dewar. It is also part of the AMPAC, GAMESS (US), PC GAMESS, GAMESS (UK), Gaussian, ORCA and CP2K programs.
Austin Model 1, or AM1, is a semi-empirical method for the quantum calculation of molecular electronic structure in computational chemistry. It is based on the Neglect of Differential Diatomic Overlap integral approximation. Specifically, it is a generalization of the modified neglect of differential diatomic overlap approximation. Related methods are PM3 and the older MINDO.
Ghemical is a computational chemistry software package written in C++ and released under the GNU General Public License. The program has graphical user interface based on GTK+2 and supports quantum mechanical and molecular mechanic models, with geometry optimization, molecular dynamics, and a large set of visualization tools. Ghemical relies on external code to provide the quantum-mechanical calculations — MOPAC provides the semi-empirical MNDO, MINDO, AM1, and PM3 methods, and MPQC methods based on Hartree–Fock calculations.
PQS is a general purpose quantum chemistry program. Its roots go back to the first ab initio gradient program developed in Professor Peter Pulay's group but now it is developed and distributed commercially by Parallel Quantum Solutions. There is a reduction in cost for academic users and a site license. Its strong points are geometry optimization, NMR chemical shift calculations, and large MP2 calculations, and high parallel efficiency on computing clusters. It includes many other capabilities including Density functional theory, the semiempirical methods, MINDO/3, MNDO, AM1 and PM3, Molecular mechanics using the SYBYL 5.0 Force Field, the quantum mechanics/molecular mechanics mixed method using the ONIOM method, natural bond orbital (NBO) analysis and COSMO solvation models. Recently, a highly efficient parallel CCSD(T) code for closed shell systems has been developed. This code includes many other post Hartree–Fock methods: MP2, MP3, MP4, CISD, CEPA, QCISD and so on.
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 (US) and GAMESS (UK) variants, which now differ significantly. GAMESS (US) is maintained by the members of the Gordon Research Group at Iowa State University. GAMESS (US) source code is available as source-available freeware, but is not open-source software, due to license restrictions.
General Atomic and Molecular Electronic Structure System (GAMESS-UK) is a computer software program for computational chemistry. The original code split in 1981 into GAMESS-UK and GAMESS (US) variants, which now differ significantly. Many of the early developments in the UK version arose from the earlier UK based ATMOL program, which, unlike GAMESS, lacked analytical gradients for geometry optimisation.
The fragment molecular orbital method (FMO) is a computational method that can compute very large molecular systems with thousands of atoms using ab initio quantum-chemical wave functions.
Gabedit is a Graphical User Interface to GAMESS (US), Gaussian, MOLCAS, MOLPRO, MPQC, OpenMopac, PC GAMESS, ORCA and Q-Chem computational chemistry packages.
Ascalaph Designer is a computer program for general purpose molecular modelling for molecular design and simulations. It provides a graphical environment for the common programs of quantum and classical molecular modelling ORCA, NWChem, Firefly, CP2K and MDynaMix . The molecular mechanics calculations cover model building, energy optimizations and molecular dynamics. Firefly covers a wide range of quantum chemistry methods. Ascalaph Designer is free and open-source software, released under the GNU General Public License, version 2 (GPLv2).
The Extensible Computational Chemistry Environment provides a sophisticated graphical user interface, scientific visualization tools, and the underlying data management framework enabling scientists to efficiently set up calculations and store, retrieve, and analyze the rapidly growing volumes of data produced by computational chemistry studies.
TeraChem is a computational chemistry software program designed for CUDA-enabled Nvidia GPUs. The initial development started at the University of Illinois at Urbana-Champaign and was subsequently commercialized. It is currently distributed by PetaChem, LLC, located in Silicon Valley. As of 2020, the software package is still under active development.
Kim K. Baldridge is an American theoretical and computational chemist who works to develop quantum mechanical methodologies and apply quantum chemical methods to problems in life sciences, materials science, and general studies. She is professor and vice dean in the School of Pharmaceutical Science and Technology of Tianjin University in China, where she also directs the High Performance Computing Center.
Theresa Lynn Windus is an American chemist who is a Distinguished Professor at Iowa State University and the Ames Laboratory. Her research involves the development and use of high performance computational chemistry methods to tackle environmental challenges, including the development of new catalysts and renewable energy sources. She was elected a Fellow of the American Chemical Society in 2020.
