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First‐Order geometrical response equations for state‐averaged multiconfigurational self‐consistent field ( SA ‐ MCSCF ) wave functions
Author(s) -
Bak Keld Lars,
Boatz Jerry,
Simons Jack
Publication year - 1991
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.560400308
Subject(s) - weighting , wave function , field (mathematics) , state (computer science) , physics , statistical physics , quantum mechanics , chemistry , mathematics , algorithm , pure mathematics , acoustics
The first‐order geometrical response equations for a state‐averaged multiconfigurational self‐consistent field ( SA ‐ MCSCF ) calculation are derived. This derivation is carried through from first principles to final working equations suited for computer implementation. The final equations are expressed such that the energies and wave functions must be known only for the internal SA ‐ MCSCF states. In the derivation, the special but important case where two or more internal states have equal weighting factors is treated in a manner fully consistent with all other cases. Except for introducing extra equations that are straightforward to solve, the case where two or more internal states have equal weighting factors introduces no new complications.