Bond orbital models. Part 1.—Atomic charges from a fully localized SCF method

Abstract

Attention is drawn to the advantages of the BO(bond orbital)–SCF model for computing atomic charges of very large systems such as polymers or molecules of biological interest, when they can be described by a dominant localized structure. This model has been found to be particularly effective at the INDO level of approximation: as compared with ab inito results, the computed charges of a variety of organic molecules are at least of the same quality as those obtained from methods of the NDO or XHMO type. The charge variations caused by substituent effects and geometrical deformations (variations in bond angles, rotations around single bonds) are also correctly predicted as a result of the explicit inclusion of hydridization. The computing times are extremely short.