Molecular systems, description, 106 Molecular theory, structure and transport, 258-266 Molecules, LDF theory, 49-66 Moller-Plesset perturbation theory use, 346 [Pg.431]

Moller-Plesset (MPn) correlated ah initio method based on perturbation theory [Pg.366]

Periodic boundary conditions, 303-305 Perturbation theory, 366. See also Moller-Plesset [Pg.378]

To obtain an improvement on the Hartree-Fock energy it is therefore necessary to use Moller-Plesset perturbation theory to at least second order. This level of theory is referred to as MP2 and involves the integral J dr. The higher-order wavefunction g is [Pg.135]

This Foek operator is used to define the unperturbed Hamiltonian of Moller-Plesset perturbation theory (MPPT) [Pg.579]

A number of types of calculations begin with a HF calculation and then correct for correlation. Some of these methods are Moller-Plesset perturbation theory (MPn, where n is the order of correction), the generalized valence bond (GVB) method, multi-conhgurational self-consistent held (MCSCF), conhgu-ration interaction (Cl), and coupled cluster theory (CC). As a group, these methods are referred to as correlated calculations. [Pg.22]

Correlation can be added as a perturbation from the Hartree-Fock wave function. This is called Moller-Plesset perturbation theory. In mapping the HF wave function onto a perturbation theory formulation, HF becomes a hrst-order perturbation. Thus, a minimal amount of correlation is added by using the second-order MP2 method. Third-order (MP3) and fourth-order (MP4) calculations are also common. The accuracy of an MP4 calculation is roughly equivalent to the accuracy of a CISD calculation. MP5 and higher calculations are seldom done due to the high computational cost (A time complexity or worse). [Pg.22]

MP2 2 Order Moller-Plesset Perturbation Theory Through 2nd derivatives [Pg.9]

MP4 4 Order Moller-Plesset Perturbation Theory (including Singles, Doubles, Triples and Quadruples by default) Energies only [Pg.9]

Another approach to electron correlation is Moller-Plesset perturbation theory. Qualitatively, Moller-Plesset perturbation theory adds higher excitations to Hartree-Fock theory as a non-iterative correction, drawing upon techniques from the area of mathematical physics known as many body perturbation theory. [Pg.267]

So far, we ve presented only general perturbation theory results.We U now turn to the particular case of Moller-Plesset perturbation theory. Here, Hg is defined as the sum of the one-electron Fock operators [Pg.268]

Perturbation theory basis for RB and RBST potentials, 179 computation of correlation energies, 207 See also Moller-Plesset perturbation theory [Pg.432]

Highest occupied molecular orbital Intermediate neglect of differential overlap Linear combination of atomic orbitals Local density approximation Local spin density functional theory Lowest unoccupied molecular orbital Many-body perturbation theory Modified INDO version 3 Modified neglect of diatomic overlap Molecular orbital Moller-Plesset [Pg.124]

These surfaces are all based on some combination of ab initio electronic structure calculations plus fitting. The AD and BM surfaces are based respectively in whole or in part on extended-basis-set single-configuration self-consistent-field calculations, whereas the RB and RBST calculations are based on calculations including electron correlation by Moller-Plesset fourth-order perturbation theory. For the rigid-rotator calculations R., the intramolecular internuclear distances R- and R [Pg.179]

A detailed study of the various possibilities in the choice of the partition to be used in performing the perturbation falls outside the scope of the present contribution (see reference [34]) here we will limit the discussion to the widely used Moller-Plesset partition [7] in which the diagonal matrix elements are defined by [Pg.43]

The methodology presented here expands the recent CASPT2 approach to more flexible zeroth-order variational spaces for a multireference perturbation, either in the Moller-Plesset scheme or in Epsein-Nesbet approach [70-72]. Furthermore, it allows for the use of a wide set of possible correlated orbitals. These two last points were discussed elsewhere [34]. [Pg.51]

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