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Improvement of an integral approximation scheme based on semiorthogonalized orbitals
Author(s) -
Osanai You,
Kashiwagi Hiroshi
Publication year - 1980
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.560170516
Subject(s) - atomic orbital , computation , scheme (mathematics) , mathematics , orbital overlap , multiple integral , order (exchange) , electron , quantum mechanics , physics , mathematical analysis , algorithm , finance , economics
In a previous paper, a scheme of integral approximation was proposed, in which a large number of two‐electron integrals containing a certain kind of orbital pairs, i.e., weakly related pairs, can be neglected. A new criterion for partitioning orbital pairs into two groups, i.e., strongly and weakly related pairs, is introduced in order to allow for neglect of more integrals without sacrificing the accuracy of a computation. Test calculations on the BH 3 C 2 H 4 complex show that by the use of the new version, results of roughly the same accuracy as was obtained by the old version is obtained by retaining 80% of the integrals used in the old version. This kind of saving is more significant for larger molecules. For example, in a calculation on Cu‐porphine with 203 CGTO ' S , the revised version will require about 2.0 × 10 6 integrals, while the original version will require about 4.5 × 10 6 . And these two approximate calculations are expected to give the results of roughly the same accuracy.