Determination of the dipole moment by semi-empirical methods: An application of the Hellmann-Feynman theorem

In this work a new procedure, based on the Hellmann-Feynman theorem, is pre sented to calculate dipole moments. The procedure is valid for semi-empiric al methods that use the ZDO approximation. In this context a new atomic dip ole parameter eta(A) is introduced. We apply our expression in MNDO calcula tions of molecules composed of atoms H, B, C, N, O, F and Cl. We present th e value of the dipole parameter eta(A) and calculate the dipole moments of molecules involving these elements. From the results, we can conclude that our expression can be used to calculate molecular dipole moments with bette r accuracy than that currently in use. (C) 1999 Published by Elsevier Scien ce B.V. All rights reserved.