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 wavefunctions. 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 D-3 and D-1 (d(9)s(1)) and the F-3 (d(8)s(2)) electronic states of atomic platinum, the D-2 d(9) State of Pt+, and the tow-lying (2) Delta, (2) Pi, and (2) Sigma(+) 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.