Spin-Orbit Coupling Effects in Di-Hydrides of Third-Row Transition Elements

摘要

Spin-orbit coupling (SOC) effects were investigated for low-lying electronic states in the di-hydrides of third-row transition elements by using MCSCF+MRMP2, +FOCI, and +SOCI methods with the SBKJC basis sets augmented by a set of f functions for transition elements and a set of p functions for hydrogen atoms, where MCSCF, MRMP2, FOCI, and SOCI are abbreviations of multi-configuration self-consistent field, multi-reference second-order Moller-Plesset, first-order configuration interaction, and second-order configuration interaction, respectively. Before the inclusion of SOC effects, six di-hydrides (LaH_2, HfH_2, TaH_2, WH_2, OsH_2, and IrH_2) are lower in energy than the corresponding dissociation limits (transition element and a hydrogen molecule). All of these di-hydrides have bent structures at their energy minima, and the ground states are ~2A_1, ~1A_1, ~4B_1, ~5B_2, ~3B_2, and ~2A_1, respectively. After the inclusion of SOC effects, the ground states are assigned to E_(1/2), A_1, E_(1/2), A_1,A_1 and E_(1/2) in the double-group representation of C_(2v) symmetry. It can be concluded that SOC effects are not so important in LaH_2, HfH_2, and TaH_2, while they become important in describing bending potential energy curves of low-lying electronic states in WH_2, OsH_2, and IrH_2.