A new mean-field and ECP-based spin-orbit method. Applications to Pt and PtH

All-electron spin-orbit mean-field integrals have been modified to be used with effective core potential valence wave-functions. Two different effective core potentials, one of the conventional Huzinaga type and the other an ab initio model potential, have been employed in our investigation. In all cases the full nodal structure of the valence orbitals has been kept. The applicability of the present approach has been tested for the 3D and 1D (d9s1) and the 3F (d8s2) electronic states of atomic platinum, the 2D d9 state of Pt+, and the low-lying 2Δ, 2Π, and 2Σ+ states of platinum hydride. Spin-orbit matrix elements evaluated for ab initio model potential wavefunctions are found to agree with all-electron results to within better than 3%, and the corresponding agreement for the spectroscopic constants of PtH is excellent.