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Direct MRCI method for the calculation of relativistic many‐electron wavefunctions. I. General formalism
Author(s) -
Esser M.
Publication year - 1984
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.560260303
Subject(s) - wave function , formalism (music) , spinor , unitary state , relativistic quantum chemistry , physics , configuration interaction , quantum mechanics , multireference configuration interaction , electronic correlation , electron , mathematical physics , chemistry , computational chemistry , molecule , art , musical , political science , law , visual arts
The formalism of a quasi‐ or full‐relativistic multireference CI method has been developed and implemented. The scheme is appropriate for the calculation of molecular systems in which the relativistic effects are of the same order of magnitude as the correlation contributions. In this contribution some important symmetry aspects of a relativistic many‐electron wave function are discussed and the consequences for the CI matrix structure are shown. An efficient CI strategy in the form of a direct CI is presented, which avoids the construction of the whole CI matrix. Based on a determinantal expansion of molecular spinor products, the individual one‐ and two‐electron molecular integrals are processed, and the molecular symmetry is easily accounted for by a proper linear combination of Slater determinants in the CI starting vector. For an efficient CI organization some powerful techniques of the graphical unitary group approach have been transferred to the relativistic case.