Accurate MRCI study of the low-lying electronic states of the AlS molecule

Abstract

In this paper, ab initio potential energy curves of the first two lowest dissociation channels of AlS have been calculated by using the complete active space self-consistent field (CASSCF) and the internally contracted multireference configuration interaction (icMRCI) method. 13 Λ–S states (X2Σ+, A'2Π, A2Σ+, a4Σ+, b4Δ, c4Σ−, D2Δ, E2Σ−, B2Π, d4Π, e4Π, 22Σ− and 24Σ−) of AlS molecule and the transition properties between these states are reported. The transition properties of A'2Π3/2_ X2Σ+1/2, and A'2Π1/2_ X2Σ+1/2 are studied with the effect of spin–orbit coupling (SOC) using the Breit-Pauli Hamiltonian. The accuracy of these potential energy curves is improved the extrapolation of the limit of the complete basis set. The spectroscopic parameters and transition properties reported in this paper are expected to provide useful guidance for future experiments, astronomical observations and theoretical research.