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Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure of many-body systems, in particular atoms, molecules, and the condensed phases. Using this theory, the properties of a many-electron system can be determined by using functionals, i.e. functions of another function. In the case of DFT, these are functionals of the spatially dependent electron density. DFT is among the most popular and versatile methods available in condensed-matter physics, computational physics, and computational chemistry.
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Coupled cluster (CC) is a numerical technique used for describing many-body systems. Its most common use is as one of several post-Hartree–Fock ab initio quantum chemistry methods in the field of computational chemistry, but it is also used in nuclear physics. Coupled cluster essentially takes the basic Hartree–Fock molecular orbital method and constructs multi-electron wavefunctions using the exponential cluster operator to account for electron correlation. Some of the most accurate calculations for small to medium-sized molecules use this method.
MOLPRO is a software package used for accurate ab initio quantum chemistry calculations. It is developed by Peter Knowles at Cardiff University and Hans-Joachim Werner at Universität Stuttgart in collaboration with other authors.
The extended Hückel method is a semiempirical quantum chemistry method, developed by Roald Hoffmann since 1963. It is based on the Hückel method but, while the original Hückel method only considers pi orbitals, the extended method also includes the sigma orbitals.
Møller–Plesset perturbation theory (MP) is one of several quantum chemistry post–Hartree–Fock ab initio methods in the field of computational chemistry. It improves on the Hartree–Fock method by adding electron correlation effects by means of Rayleigh–Schrödinger perturbation theory (RS-PT), usually to second (MP2), third (MP3) or fourth (MP4) order. Its main idea was published as early as 1934 by Christian Møller and Milton S. Plesset.
Per-Olov Löwdin was a Swedish physicist, professor at the University of Uppsala from 1960 to 1983, and in parallel at the University of Florida until 1993.
In computational chemistry, post–Hartree–Fock methods are the set of methods developed to improve on the Hartree–Fock (HF), or self-consistent field (SCF) method. They add electron correlation which is a more accurate way of including the repulsions between electrons than in the Hartree–Fock method where repulsions are only averaged.
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Ab initio quantum chemistry methods are computational chemistry methods based on quantum chemistry. The term ab initio was first used in quantum chemistry by Robert Parr and coworkers, including David Craig in a semiempirical study on the excited states of benzene. The background is described by Parr. Ab initio means "from first principles" or "from the beginning", implying that the only inputs into an ab initio calculation are physical constants. Ab initio quantum chemistry methods attempt to solve the electronic Schrödinger equation given the positions of the nuclei and the number of electrons in order to yield useful information such as electron densities, energies and other properties of the system. The ability to run these calculations has enabled theoretical chemists to solve a range of problems and their importance is highlighted by the awarding of the Nobel prize to John Pople and Walter Kohn.
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Symmetry-adapted perturbation theory or SAPT is a methodology in electronic structure theory developed to describe non-covalent interactions between atoms and/or molecules. SAPT is a member of the family of methods known as energy decomposition analysis (EDA). Most EDA methods decompose a total interaction energy that is computed via a supermolecular approach, such that:
FHI-aims is a shared-source software package for computational molecular and materials science written in Fortran. It uses density functional theory and many-body perturbation theory to simulate chemical and physical properties of atoms, molecules, nanostructures, solids, and surfaces. Originally developed at the Fritz Haber Institute in Berlin the ongoing development of the FHI-aims source code is now driven by a world-wide community of collaborating research institutions.
References
- ↑ Balabin, Roman M. (2008). "Enthalpy difference between conformations of normal alkanes: Intramolecular basis set superposition error (BSSE) in the case of n-butane and n-hexane". J. Chem. Phys. 129 (16): 164101. Bibcode:2008JChPh.129p4101B. doi:10.1063/1.2997349. PMID 19045241.CS1 maint: discouraged parameter (link)
- 1 2 Hobza, Pavel; Müller-Dethlefs, Klaus (2010). Non-covalent Interactions: Theory and Experiment (PDF). Cambridge, England: Royal Society of Chemistry. p. 13. ISBN 978-1-84755-853-4. Archived from the original (PDF) on 2011-06-06. Retrieved 2010-05-21.
- 1 2 Liedl, Klaus R. (1998). "Dangers of counterpoise corrected hypersurfaces. Advantages of basis set superposition improvement". The Journal of Chemical Physics. 108 (8): 3199–3204. Bibcode:1998JChPh.108.3199L. doi:10.1063/1.475715.
- ↑ Mayer, I.; Valiron, P. (1998). "Second order Møller–Plesset perturbation theory without basis set superposition error". J. Chem. Phys. 109 (9): 3360–3373. Bibcode:1998JChPh.109.3360M. doi:10.1063/1.476931.
- ↑ Bende, Attila. "THE CHEMICAL HAMILTONIAN APPROACH (CHA)" . Retrieved 14 May 2010.CS1 maint: discouraged parameter (link)
- ↑ Van Duijneveldt, Frans B.; van Duijneveldt-van de Rijdt, Jeanne G. C. M.; van Lenthe, Joop H. (1994). "State of the art in counterpoise theory". Chem. Rev. 94 (7): 1873–1885. doi:10.1021/cr00031a007.
- ↑ Rösch, N. (2003). "Counterpoise Correction". Technical University of Munich, Quantum Chemistry Laboratory. Archived from the original on 18 April 2015. Retrieved 14 May 2010.CS1 maint: discouraged parameter (link)
- ↑ Sedano, Pedro Salvador (2000). "Counterpoise Corrected Potential Energy Surfaces". University of Girona. Retrieved 14 May 2010.CS1 maint: discouraged parameter (link)
- ↑ Paizs, Béla; Suhai, Sándor (1998). "Comparative study of BSSE correction methods at DFT and MP2 levels of theory". J. Comput. Chem. 19 (6): 575–584. doi:10.1002/(SICI)1096-987X(19980430)19:6<575::AID-JCC1>3.0.CO;2-O.
- ↑ Mentel, Lukasz; Baerends, Evert Jan (2013). "Can the Counterpoise Correction for Basis Set Superposition Effect Be Justified?". J. Comput. Chem. 10 (1): 252–267. doi:10.1021/ct400990u. PMID 26579908.
- ↑ Mayer, I. (2004). "Interrelations between the a priori and a posteriori BSSE correction schemes". Int. J. Quantum Chem. 100 (4): 559–566. doi:10.1002/qua.10827.
