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Improved CI formula evaluation: Elimination of the phase determination at the determinant level for arbitrarily coupled CSF s
Author(s) -
Bauschlicher Charles W.,
Lengsfield Byron H.
Publication year - 1981
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.560190416
Subject(s) - coincidence , phase (matter) , matrix (chemical analysis) , work (physics) , state (computer science) , mathematics , computational chemistry , statistical physics , physics , chemistry , algorithm , quantum mechanics , chromatography , alternative medicine , pathology , medicine
The amount of work needed to evaluate the matrix elements in a configuration interaction calculation can be very large. This is especially true if the phase associated with bringing determinants into maximum coincidence is evaluated at the determinant level. A method is presented which allows the phase to be determined at the occupation level for arbitrarily coupled configuration state functions.