Semiempirical studies of core electron binding energies Part II. SCC-MO Calculations for uracil and its derivatives

Abstract

The solid-state binding energies of uracil and some of its derivatives have been calculated using semiempirical SCC-MO intramolecular potential expressed in the pointcharge approximation. The results are essentially in satisfactory agreement with experimental data, giving at the same time a simple and transparent interpretation of the ESCA spectra which is close to that suggested by chemical intuition. Splitting of some unresolved N 1 s peaks is proposed, and separate binding energies are attributed to particular nitrogen atoms. The relaxation energies are discussed briefly. The present and earlier evidence indicates that formal atomic charges are meaningful within the theoretical framework adopted, despite the fact that they cannot be defined in a unique fashion.