Zw. Su, NEW METHOD FOR THE DERIVATION OF NET ATOMIC CHARGES FROM THE ELECTROSTATIC POTENTIAL, Journal of computational chemistry, 14(9), 1993, pp. 1036-1041
Net atomic charges are derived from a least-squares fitting to electro
static potentials at atomic sites. The method treats atoms in the mole
cule as having spherically averaged Hartree-Fock densities, the atomic
densities overlapping with one another. The method has the advantage
of best reproducing the electrostatic potentials at the atomic nuclei
and avoiding the arbitrariness in choosing the points used in the fitt
ing. We have written a FORTRAN program, CHELPN92 (Z. Su, Chemistry Dep
artment, SUNY at Buffalo, Buffalo, NY, 1992), based on the method and
applied it to deuterated benzene, l-alanine, d,l-histidine, 2-methyl-4
-nitroaniline, and deuterated pyridinium-1-dicyanomethylide using the
molecular geometry and electrostatic potentials from analysis of accur
ate X-ray diffraction data. The derived charges are used to calculate
the molecular dipole moments. While the charges from this method are i
n general significantly different from those from the kappa refinement
[P. Coppens, T.N. Guru Row, P. Leung, E.D. Stevens, P.J. Becker, and
Y.W. Yang, Acta Cryst. A, 35, 63 (1979)], the dipole moments obtained
with the new method agree well with those from the kappa refinement. (
C) 1993 by John Wiley & Sons, Inc.