Ab initio study of spin–orbit interaction in the ground electronic states of XH (X = C, Si, Ge and Sn) molecules

Abstract

Electronic structure and spectroscopic properties for the ground electronic states of CH, SiH, GeH and SnH molecules were obtained using the multiconfigurational self-consistent field followed by spin–orbit multireference multistate perturbation theory. Spin–orbit splitting calculations for ground states of the four molecules were carried out with model core potential (MCP) and all-electron (AE) methods. MCP results are compared with corresponding AE values to estimate the accuracy of the saving cost MCP calculations. The potential energy curves, calculated for the Ω states CH( X 1 2Π 1/2 and X 2 2Π 3/2), SiH( X 1 2Π 1/2 and X 2 2Π 3/2), GeH( X 1 2Π 1/2 and X 2 2Π 3/2) and SnH( X 1 2Π 1/2 and X 2 2Π 3/2) using the MCP method, were fitted to analytical potential energy function using Murrell–Sorbie potential energy function. Based on the analytical potential energy function, force constants and spectroscopic constants for the Ω states were obtained.