Electronic Spectrum of Silicon Monosulfide: Configuration Interaction Study

Abstract

Ab initio based configuration interaction calculations using relativistic effective core potentials and compatible basis sets have been performed to study the electronic spectrum of the silicon monosulfide molecule. Potential energy curves of low-lying states of SiS have been computed. Spectroscopic properties of many observed states such as X1Σ+, a3Σ+, d3Δ, b3Π, C1Σ-, e3Σ-, D1Δ, A1Π, and E1Σ+ up to 42 000 cm-1 of energy have been calculated and compared. The ground state of SiS is represented mainly by ...π4 (74%) and ...π3π* (12%) configurations with re = 1.957 A (3.7 a0) and ωe = 733 cm-1, which compare well with the observed values. The dissociation energies of the ground and excited states have been estimated. All 18 Λ-S states correlating with the lowest asymptote have been allowed to mix through the spin−orbit coupling. Effects of spin−orbit interactions on the potential energy curves and spectroscopic properties of the low-lying states of SiS are studied. Dipole-allowed transitions such as E−X and...