A NEW MEAN-FIELD AND ECP-BASED SPIN-ORBIT METHOD - APPLICATIONS TO PTAND PTH

All-electron spin-orbit mean-field integrals have been modified to be used with effective core potential valence wavefunctions. Two differen t effective core potentials, one of the conventional Huzinaga type and the other an ab initio model potential, have been employed in our inv estigation. In all cases the full nodal structure of the valence orbit als 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)) electroni c states of atomic platinum, the D-2 d(9) State of Pt+, and the tow-ly ing (2) Delta, (2) Pi, and (2) Sigma(+) states of platinum hydride. Sp in-orbit matrix elements evaluated for ab initio model potential wavef unctions are found to agree with all-electron results to within better than 3%, and the corresponding agreement for the spectroscopic consta nts of PtH is excellent.