Intermediate neglect of differential overlap spectroscopic studies on lanthanide complexes - I. Spectroscopic parametrization and application to diatomic lanthanide oxides LnO (Ln=La, Ce, Gd, and Lu)

The Intermediate Nelgect of Differential Overlap model for spectroscopy has been extended to lanthanide complexes by including spin-orbit coupling. The method uses atomic spectroscopy and model Dirac-Fock calculations on the lanthanide atoms and ions to obtain ionization potentials, Slater-Condon factors and basis sets. The spin-orbit interaction strength, ζ(nl), is acquired from atomic spectroscopy, and only one-center terms are formally included. Calculation then proceeds using one open-shell operator for all seven f-orbitals initially assumed degenerate to generate starting non-relativistic molecular orbitals for the subsequent configuration-interaction and spin-orbit calculation. Calculations are performed on the monoxides La, Ce, Gd, and Lu where there are ample experimental assignments. In general, the results are quite good, suggesting that the calculated energies, oscillator strengths and spin-orbit splittings can be used with success in assigning spectra, even in those cases where jj-coupling is of intermediate strength.