New insight into the spectroscopy of LaH by ab-initio methods

Abstract

By ab-initio methods, the spectroscopy of lanthanum hydride molecule LaH is predicted and the states involved in all the observed band systems are assigned. So, 34 low - lying 1,3Λ(±) states located below 31400 cm−1 are calculated and 67 Ω(±) states are generated by taking into account the spin–orbit coupling effect of lanthanum. For these states, the spectroscopic constants such as Re, Te, ωe and ωeχe are determined and the potential energy curves (PECs) are plotted in the range of internuclear distance from 1.00 Å to 3.00 Å. The calculated electronic configuration of 1,3Λ(±) states shows the ionic nature La+H- of this species. Moreover, the composition of the Ω(±) state-wave functions in term of Λ-S parent states are calculated at the equilibrium internuclear distance of the ground state. Indeed, this molecule belongs to Hund’s case (c) since the transition in many observed band systems only obeys the rule ΔΩ = 0, ±1.