CAS calculations for the ground- and excited-state properties of HSO radical

We optimized the structures of ground state and three low-lying excited states for HSO radical using the CASSCF method with ANO-L basis sets. Their single-point energy calculations were performed at the CASPT2 level including more electronic dynamic correlation effects. The results of frequency calculations show that these structures are minimum points on the potential energy surface. The variations of geometry parameters between the ground and excited states were rationalized by the analysis of their electronic structures. The calculated results fall well within the range of reported values.