Estimation of atomic charges by an electronegativity equalization procedure calibrated with core binding energies

A simple procedure, based on the equalization of orbital electronegativities, has been devised for calculating atomic charges in molecules. The calculation involves four empirical parameters (only two of which are needed for most molecules) which have been evaluated by application of the potential model equation for calculating core binding energies to 126 experimental ls binding energies for 66 gaseous compounds. The method yields standard deviations in the binding energies of carbon, nitrogen, oxygen, and fluorine of ±0.69, ±0.53, ±0.74, and ±0.36 eV, respectively. The calculated and experimental binding energies are used to test the expected correlation between the ligancy of an ionizing atom and the electronic relaxation energy and to test the "transition state" method of providing for relaxation energy .