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Applicability of non‐degenerate many‐body perturbation theory to quasidegenerate electronic states: A model study
Author(s) -
Wilson S.,
Janmkowski K.,
Paldus J.
Publication year - 1983
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560230508
Subject(s) - degenerate energy levels , perturbation theory (quantum mechanics) , configuration interaction , basis set , ab initio , excitation , physics , full configuration interaction , electronic correlation , perturbation (astronomy) , quantum mechanics , computational chemistry , electron , atomic physics , chemistry , density functional theory , molecule
The nondegenerate finite‐order many‐body perturbation theory is applied to simple model systems in which the degree of quasidegeneracy can be continuously varied over a wide range. Three ab initio minimum basis set models involving four hydrogen atoms in various spatial arrangements are considered. The results are compared with the exact full configuration‐interaction approach, double‐excitation configuration‐interaction and the coupled‐pair many‐electron theory.