Inner-electron ionisation energies of small molecules

Wavefunctions for the inner-shell hole states and parent molecules of a series of first-row oxygen- and carbon-containing molecules are obtained using the restricted self-consistent field method. A minimum basis set (STO-5G) was used for all the calculations, and the exponents for each state were found using Slater's rules. The results show that the relaxation energy of the outer electrons is dependent on the atomic environment. In general, the chemical shifts reported here are in closer agreement with experiment than those obtained using Koopmans' theorem. The calculations are also extended to molecules containing second-row atoms.