Ab initio calculations of the lowest 262s+1Λ± electronic states of 90ZrS including spin-orbit coupling

Abstract

The electronic structure in the representation2S + 1Λ± of the diatomic molecule 90ZrS is carried out using (CASSCF/MRCI- single and double excitation)) ab-initio methods. In this work, 14 singlet and 12 triplet electronic states of energies below 36,000 cm−1, of which 8 singlet and 6 triplet excited states yet unobserved experimentally, are predicted.The potential energy curves (PECs) of these states are also computed in an interval of internuclear distances from about 1.5 Å to 4.0 Å. The spectroscopic constants ωe and ωeχe, the internuclear distance Re and the energy at equilibrium Te of the singlet and triplet states referred to the ground state energy at equilibrium are calculated and compared with previous experimental and theoretical results. The permanent electric dipole moments for these states are calculated for R around the equilibrium internuclear distances. The allowed transition dipole moments (TDM) between the calculated singlet and triplet states of 90ZrS molecule are also displayed.As a result of the spin orbit coupling (SOC) calculations, 52 electronic Ω(±) components generated in almost from the 26 states 2S + 1Λ± are obtained. This work has determined that the ground state is (X)1Σ+ with an equilibrium internuclear distance Re = 2.15 Å. However, the (1)3Δ1 is found very close to (X)1Σ+ situated 180 cm−1 above it, with an internuclear distance Re = 2.19 Å and becomes the lowest state after Re = 2.21 Å.