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Approximate fourth‐order perturbation theory of the electron correlation energy
Author(s) -
Krishnan R.,
Pople J. A.
Publication year - 1978
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.560140109
Subject(s) - electronic correlation , perturbation (astronomy) , perturbation theory (quantum mechanics) , electron , physics , statistical physics , correlation , order (exchange) , møller–plesset perturbation theory , quantum mechanics , mathematical physics , mathematics , geometry , economics , finance
An approximate fourth‐order expression for the electron correlation energy in the Møller–Plesset perturbation scheme is proposed. It takes into account all the contributions to the fourthorder energy neglecting only those of the triple‐substituted determinants. It is size consistent and correct to fourth order for an assembly of isolated two‐electron systems. Illustrative calculations are reported for a series of small molecules.