INCORPORATION OF SOLVENT EFFECTS INTO AB-INITIO MOLECULAR-ORBITAL CALCULATIONS BY THE GENERALIZED BORN FORMULA - FORMULATION, PARAMETERIZATION, AND APPLICATIONS

A recently developed method for incorporation of solvent effects into ab initio SCF calculations using the generalized Born formula was modi fied by (i) introducing a steric factor which accounts for the exclusi on of the solvent shell of an atom in a molecule by the other atoms, a nd (ii) re-determination of the parameters used to evaluate the atomic radii which are expressed as a function of the atomic charge obtained by Lowdin population analysis. The hydration free energies of neutral molecules, cations, and anions are calculated semi-quantitatively by the new version of the method. The results of its application to the S (N)2 reaction of Cl- and CH3Cl, the S(N)1 ionic dissociation of t-BuCl , and the internal rotation in formamide are presented. (C) 1997 Elsev ier Science B.V.