I. Rozas, ATOMIC CHARGES DERIVED FROM DIFFERENT METHODS - A COMPARATIVE-STUDY APPLIED TO SO2 HETEROCYCLES, International journal of quantum chemistry, 62(5), 1997, pp. 477-487
Atomic charges were calculated at ab initio level using different meth
ods of charge determination to compare them and estimate their utility
in the electronic description of heterocycles containing the SO2 moie
ty. Those procedures implemented on the Gaussian92 program were includ
ed [Mulliken population analysis, Weinhold-Reed natural population ana
lysis (NPA) and CHELPG]. The first two are based on the molecular orbi
tals while in the third one the charges are derived by fitting the ele
ctrostatic potential. Two sets of compounds were chosen to represent t
he different characteristics of the SO2 heterocycles studied: simpler
five-member heterocycles and SO2 small derivatives. These molecules we
re optimized at the HF/6-31G level and their energy evaluated by a pu
nctual calculation MP2/6-31G//HF/6-31G*. The dipole moments for these
molecules were obtained by using all the methods previously mentioned
and compared with the SCF, MP2, and experimental dipole moments. The
influence on the charges of some atoms by changing the electronegativi
ty of neighboring atoms has also been investigated for these compounds
. The results obtained show that the best methods to describe the elec
tronic distribution of the oxathiole studied are Mulliken and CHELPG a
t the MP2 level of calculation. The charge distributions obtained with
these two methods for these particular heterocycles are discussed. (C
) 1997 John Wiley & Sons, Inc.