Accurate spectroscopic calculations of the 21 Λ-S states and 42 Ω states of the SiB radical.

The potential energy curves were calculated for the 21 Λ-S states, which were generated from the first two dissociation channels, Si(P)+B(P) and Si(D)+B(P), of the SiB radical. The potential energy curves were computed for the 42 Ω states, which arose from the 21 Λ-S states. The calculations were done using the CASSCF method, which was followed by the icMRCI approach. Of these 21 Λ-S states, the DΣ, iΣ, jΠ, 5Π, and 1Φ states had double wells. The DΣ, aΠ, AΠ, eΠ, jΠ, 5Π, hΔ, and 1Φ states were inverted with the spin-orbit coupling effect taken into account. The 3Δ state and the second wells of DΣ and 1Φ states were weakly bound. Core-valence correlation correction, scalar relativistic correction and Davidson correction were included. The spectroscopic parameters were determined and the vibrational properties of some weakly-bound states were predicted. The spin-orbit coupling effect on the spectroscopic parameters was evaluated. Comparison with available experimental data shows that the methodology used is highly accurate for the SiB radical.