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Exact size consistency of multireference Møller–Plesset perturbation theory
Author(s) -
van Dam Huub J. J.,
van Lenthe Joop H.,
Ruttink Paul J. A.
Publication year - 1999
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/(sici)1097-461x(1999)72:6<549::aid-qua2>3.0.co;2-g
Subject(s) - hamiltonian (control theory) , møller–plesset perturbation theory , chemistry , excitation , perturbation theory (quantum mechanics) , perturbation (astronomy) , multireference configuration interaction , quantum mechanics , computational chemistry , physics , density functional theory , mathematics , basis set , mathematical optimization
Abstract Single‐reference closed‐shell Møller–Plesset perturbation theory is well known for its size consistency, a quality that is essential for consistent comparisons of calculations on molecules of different size. However, it is far from obvious whether this quality can be retained in the multireference case. In this work it is shown that an exactly size consistently generalization to multireference perturbation theory can be constructed. The central result is that the zeroth‐order Hamiltonian should be constructed using separate projection operators for each excitation level, i.e., it should contain no couplings between different excitation levels. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 549–558, 1999