Wood-Boring ab initio model potential relativistic treatment of Ce and CeO

A simple, approximate method of simultaneously handling the 5s and 6s valence orbitals of the lanthanide elements in Wood-Boring based relativistic ab initio core model potential calculations (WB-AIMP), which had previously been formulated with the restriction of having only one valence orbital with a given l, is presented. Its applicability is shown in spin-orbit configuration interaction calculations on Ce and spin-free calculations on CeO. The good quality of the Wood-Boring spin-orbit operators of Ce is shown and a recommended contraction of its valence basis set is established. These results support the production of WB-AIMP data for the lanthanide series.