SPECTROSCOPIC CONSTANTS AND POTENTIAL-ENERGY CURVES OF ELECTRONIC STATES OF LAH

Spectroscopic parameters (re, Te, ωe, D3, μe) and potential energy curves are computed for the low-lying states of LaH using complete active space MCSCF (CASSCF) followed by second-order configuration interaction (SOCI) calculations. Relativistic CI (RCI) calculations were carried out to study the effect of spin-orbit coupling on five low-lying λ-s states. The ground state of LaH is found to be of 1Σ+ symmetry with re = 2.08 Å, ωe=1433 cm-1, De=2.60 eV, and μe=2.42 D. The experimentally observed B↔ C→A, and b↔a band systems are reassigned as B 1Π(II)↔X 1Σ+, C 1Π(III)→X 1Σ+, and b 3Δ(III)↔a 3Π transitions. © 1990.