General system partitioning in the many-electron correlation problem for atomic and molecular systems is addressed within the spinshift formalism. The conventional method of the unitary group subduction coefficient expansion is reconsidered in the latter framework and an orbital-level factorization
Electron correlation: The many-body problem at the heart of chemistry
✍ Scribed by David P. Tew; Wim Klopper; Trygve Helgaker
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 657 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The physical interactions among electrons and nuclei, responsible for the chemistry of atoms and molecules, is well described by quantum mechanics and chemistry is therefore fully described by the solutions of the Schrödinger equation. In all but the simplest systems we must be content with approximate solutions, the principal difficulty being the treatment of the correlation between the motions of the many electrons, arising from their mutual repulsion. This article aims to provide a clear understanding of the physical concept of electron correlation and the modern methods used for its approximation. Using helium as a simple case study and beginning with an uncorrelated orbital picture of electronic motion, we first introduce Fermi correlation, arising from the symmetry requirements of the exact wave function, and then consider the Coulomb correlation arising from the mutual Coulomb repulsion between the electrons. Finally, we briefly discuss the general treatment of electron correlation in modern electronic‐structure theory, focussing on the Hartree‐Fock and coupled‐cluster methods and addressing static and dynamical Coulomb correlation. © 2007 Wiley Periodicals, Inc. J Comput Chem 28: 1307–1320, 2007
📜 SIMILAR VOLUMES
An attempt has been made to understand the structure of the Clifford algebra unitary group adapted many-particle states from the conventional symmetric group point of view. Emphasizing the symmetric group result that the consideration of the spin-independent Hamiltonian matrix over the many-particle
For the treatment of electron correlation, one most often uses the Ž . Møller᎐Plesset MP partition which defines the zero-order Hamiltonian through the spectral resolution of the Fockian. We investigate how the MP partitioning can be Ž . improved while still using the Hartree᎐Fock HF reference state
using the group symmetrical localized molecular orbitals (SLhfOs) as configuration-generating orbitals (CGOs) of many-electron wave functions, the symmetry adaptation of many-electron spaces is greatly simplified, and novel orthogonal bonded functions (OBFs), as complete space-and spin-adapted antis