Electron removal energies in Kohn-Sham density-functional theory

Talman and co-workers have presented a realization of the exact Kohn-Sham density-functional theory, neglecting correlation. From their numerical results we conclude that the occupied orbital energy eigenvalues of the local-spin-density (LSD) approximation for exchange and correlation are close to the exact Kohn-Sham orbital energies (apart from a constant shift), but that the latter do not accurately predict the removal energies of tightly-bound electrons in atoms, molecules, and solids. For the calculation of these removal energies, we propose an add-on, single-shot self-interaction correction (SIC) to the LSD orbital energies, based on a simplification and representation-invariant transformation of the original SIC method. This correction's relationship to the Dyson mass operator is briefly discussed.