An approximate method for treating spin-orbit effects in platinum

Spin-orbit coupling in platinum-containing species can be treated via a one-electron spin-orbit operator and a single scaling parameter Zeff(Pt) in conjunction with an effective core potential for the description of scalar relativistic effects. Our calibration calculations cover the five low-lying electronic states of platinum hydride PtH and the lowest fourteen levels in the atomic spectrum of the platinum atom Pt. Here, qualitative and semi-quantitative agreement between the presented semi-empirical approach and four-component Dirac-Fock calculations is found if Zeff(Pt) is chosen between 950 and 1200. Further applications concern the low-lying levels of the platinum cation Pt+, the theoretical determination of ground states for the diatomic oxides PtO and PtO+ as well as spin-orbit effects in the cationic carbene complex PtCH2+.