AnINDO/S-CI treatment including spin-orbit interaction based on Rumer spin functions. Application to the hydrated cerium ion

Abstract

We examine the inclusion of spin-orbit effects within the Rumer configuration interaction technique and discuss its implementation in the spectroscopic version of the intermediate neglect of differential overlap model (INDO/S-CI). An efficient strategy for calculating excitation energies, transition moments, and Mulliken populations for Rumer-adapted functions is described. As an example, results are presented for the ground and excited states of the hydrated trivalent cerium ion [Ce(H2O)9]3+, which confirm the low energy assignments to 4ƒ → 5 d transitions split by some 10000 cm−1 through spin-orbit coupling and ligand field interaction. Comparisons are made between this technique and one that we have used previously that utilizes configuration interaction over double-group adapted linear combinations of determinants.