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Improved intermolecular SCF theory and the BSSE problem
Author(s) -
Mayer I.,
Surján P. R.
Publication year - 1989
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.560360307
Subject(s) - delocalized electron , intermolecular force , dimer , hamiltonian (control theory) , basis set , basis (linear algebra) , superposition principle , computational chemistry , chemistry , atomic orbital , interaction energy , potential energy , water dimer , physics , statistical physics , quantum mechanics , molecule , mathematics , density functional theory , geometry , hydrogen bond , mathematical optimization , electron , organic chemistry
Analytical and numerical studies are performed concerning the exclusion of the basis set superposition error ( BSSE ) from the SCF calculations of intermolecular interactions. Based on these studies a new procedure is proposed, which consists of the following steps: (1) determine the orbitals by the SCF scheme based on the recent “chemical Hamiltonian approach” ( CHA‐SCF method), i.e., excluding the delocalization effects caused by BSSE , and then (2) calculate the usual energy expectation value. (This gives results superior to those obtained by the previous nonsymmetric CHA energy formula.) The actual numerical calculations performed for different simple systems (He 2 , water dimer) by using various basis sets indicate that the CHA/CE ( CHA with “conventional energy” formula) potential curves are well‐balanced and are close to those obtained by the Boys–Bernardi ( BB ) method and usually (but not necessarily) go slightly beyond the latter. So our method gives results better than (or close to) those given by the BB method by performing only a single ∼N 4 calculation at each geometrical arrangement of the system.