Search results
Results From The WOW.Com Content Network
In computational chemistry, post–Hartree–Fock [1] [2] (post-HF) 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 ...
Upload file; Search. Search. Appearance. Donate; ... Download as PDF; Printable version; ... Pages in category "Post-Hartree–Fock methods" The following 5 pages are ...
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.
The first term in the above expansion is normally the Hartree–Fock determinant. The other CSFs can be characterised by the number of spin orbitals that are swapped with virtual orbitals from the Hartree–Fock determinant. If only one spin orbital differs, we describe this as a single excitation determinant.
In contrast to unrestricted Hartree–Fock (UHF), the ROHF wave function is a satisfactory eigenfunction of the total spin operator, (i.e. no spin contamination is observed). Developing post-Hartree–Fock (post-HF) methods based on a ROHF wave function is inherently more difficult than using a UHF wave function, due to the lack of a unique set ...
Modern valence bond theory is the application of valence bond theory (VBT) with computer programs that are competitive in accuracy and economy, with programs for the Hartree–Fock or post-Hartree-Fock methods. The latter methods dominated quantum chemistry from the advent of digital computers because they were easier to program. The early ...
Spartan is a molecular modelling and computational chemistry application from Wavefunction. [2] It contains code for molecular mechanics, semi-empirical methods, ab initio models, [3] density functional models, [4] post-Hartree–Fock models, [5] thermochemical recipes including G3(MP2) [6] and T1.
Most include the Hartree–Fock (HF) and some post-Hartree–Fock methods. They may also include density functional theory (DFT), molecular mechanics or semi-empirical quantum chemistry methods. The programs include both open source and commercial software. Most of them are large, often containing several separate programs, and have been ...