Relativistic contributions to the low-lying excitation energies and ionization potentials of the transition metals

Numerical Hartree–Fock calculations have been performed for the lowest terms of the dns2, dn+1s, and dn+2 configurations of the neutral transition metal atoms and the dns and dn+1 configurations of the ions. The excitation energies and ionization potentials are compared with their relativistic counterparts calculated according to the approximate scheme of Cowan and Griffin. The relativistic corrections are large, surprisingly so even for the first transition series, and act to stabilize ’’s-electron rich’’ configurations. They are thus of opposite sign to the electron correlation contributions, which generally tend to stabilize ’’d-electron rich’’ configurations. These correlation effects are particularly severe towards the end of the first transition series. Estimates for relativistic corrections from perturbation theory agree well with relativistic SCF calculations for the first and second transition series but depart substantially for the third series. The excitation and ionization energies from the relativistic calculations are compared with the experimental values (averaged over J states) to observe the overall trends in the correlation contributions.