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Internal orbitally resolved charge sensitivity analysis
Author(s) -
Nalewajski Roman F.
Publication year - 1992
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.560440106
Subject(s) - intramolecular force , chemistry , eigenvalues and eigenvectors , charge (physics) , sensitivity (control systems) , ground state , diagonal , atomic physics , electron , molecular orbital , atomic orbital , matrix (chemical analysis) , population , computational chemistry , physics , molecule , quantum mechanics , mathematics , geometry , stereochemistry , demography , chromatography , electronic engineering , sociology , engineering
The intramolecular (internal) charge sensitivity analysis ( ICSA ) is presented in the molecular orbital ( MO ) resolution, with diagonal idempotency constraints being imposed on the MO occupations, n , which can then be considered as independent electron population variables of the system for the assumed fixed shapes of MOS . The standard closed‐shell (C.S.) SCF MO framework is adopted with the energy function E ( n ) approximated by the average energy of a configuration expression to cover fractional MO occupations. The components of the gradient of the auxiliary energy function, including the constraint terms, with respect to n , identified as negative MO internal electron potentials, vanish identically for the ground‐state c.s. configuration, whereas their responses to hypothetical intramolecular charge displacements assure the system stability. An application of the ICSA to the iterative SCF procedure is suggested. Illustrative results for the water molecule are reported and general properties of molecular normal orbitals (eigenvectors of the hardness matrix) are discussed. © 1992 John Wiley & Sons, Inc.