SCF and limited CI calculations on the ls shake-up spectrum of H 2O

Abstract

Open shell SCF and internal CI calculations have been performed for seven shake-up configurations of H 2O. SCF calculations on at least one of the two doublet states were carried out for each shake-up configuration. The internal CI calculations were performed using appropriate MO's. In all configuration state functions appearing in the CI the ls shell was kept singly occupied. The computed energies were much less sensitive to the choice of MO's than were the computed intensities. An assignment of the spectrum based on calculated energies and intensities was made. Shake-up energies were also computed using a CI expansion comprising all configurations, singly excited with respect to the ls hole state, allowing the unpaired ls electron to have α and β spin. A comparison of the result's obtained with the two methods was made.