Calculation of excitation and photoionization spectra by quasi‐degenerate perturbation theory

Abstract

The ability of the QDFT CI method, in which the quasi-degenerate perturbation theory is applied within the configuration interaction (CI) approach, in dealing with the calculation of excitation and photoionization spectra is shown through an overview of comparisons between the QDFT CI values and the full CI ones in the same basis set. A direct comparison with the experimental data is given for the core photoelectron spectrum of Ne and the valence photoelectron spectra of Ar and HC1. The quality of the results obtained is very satisfactory, both as regards the energies and the wave functions, indicating the validity and the flexibility of the method that can confidently be applied also in cases where strong correlation effects are present. 0 1994 John Wiley t Sons, Inc.