Calculations of core‐electron binding energies by transition operator method followed by Rayleigh–Schröudinger perturbation theory

Abstract

Vertical ionization potentials for core orbitals of HF, HzO, and CO are calculated with the a6 initio transition operator method. The results are improved by third-order Rayleigh-Schrodinger perturbation theory. The effect of basis sets is also investigated. The computed core-electron binding energies are compared with the experimental values and with those obtained by other theoretical methods. The comparison shows that the present approach leads to reliable core ionization energies, the average absolute deviation from experiment being only 0.4 eV for the cases studied.

Applied quantum chemistry

“…This success has been attributed to the fact that for core ionizations the relaxation correction to Koopmans' theorem dominates over the correlation terms. Accordingly, the transition operator method (TOM), which takes into account this orbital relaxation effect, is expected also to yield reliable core ionization potentials [207].…”