ATOMIC FUKUI FUNCTION INDEXES AND LOCAL SOFTNESS AB-INITIO

The complete and original calculation scheme beyond the finite differe nce approximation, for the atomic (and orbital) Fukui function (FF) in dices is proposed. The method explores an expansion for derivatives of LCAO coefficients, partial derivative C/partial derivative N = CU. Th e separation scheme for the U matrix has been elaborated at the ab ini tio level. Nucleophilic and electrophilic FF indices, as well as atomi c softness, have been derived from the standard result of SCF HF ab in itio calculations. The indices reproduce two effects; the change in or bital occupancy and the relaxation of the electronic system. The molec ular hardness (softness) provided by this scheme explicitly includes t hese two effects. (C) 1998 American Institute of Physics. [S0021-9606( 98)02737-8].