Rayleigh–Schrödinger perturbation theory for many-electron systems with partitioning of configurations by orders of excitation

✍ Scribed by William J. Taylor

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 592 KB
• Volume: 23
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560230446

✦ Synopsis

Abstract

Rayleigh–Schrödinger perturbation theory for many‐electron systems has been rederived by an extension of Löwin's partitioning method in which excited configurations are further partitioned by their orders (two equivalent definitions of the order of a configuration are given). The resulting equations show explicitly how first‐, second‐, and third‐order configurations contribute to the first three orders of perturbative corrections to the ground‐state wave function, and the first six orders of corrections to the energy. Because the partitioning is by orders of configurations (rather than level, i.e., single, double, etc., excitations) the formalism is unaffected by the applicability, or nonapplicability, of Brillouin's theorem.