Multireference configuration interaction study of ground and low-lying excited states of BrO radical

Abstract

This work explored the spectroscopic parameters and vibrational properties of 12 states of BrO radical. The 12 states were X2Π, A2Π, 12Δ, 12Σ+, 12Σ−, 22Σ−, a4Σ−, 24Σ−, 14Σ+, 14Δ, 14Π, and 24Π, which were generated from the first dissociation limit, Br(2Pu)+O(3Pg). The potential energy curves were calculated with the CASSCF method, which was followed by the icMRCI approach with Davidson correction. Of the 12 electronic states, the 24Π state was repulsive. Each state had the single well and only the A2Π state had one barrier. The 12Δ, 12Σ+, 12Σ−, 22Σ−, 24Σ−, 14Σ+, 14Δ and 14Π states had only several vibrational levels and were very weakly-bound states, which well depths were less than 110cm−1. To improve the quality of potential energy curves, core-valence correlation and scalar relativistic corrections as well as the extrapolation to the complete basis set limit were included. The spectroscopic parameters and vibrational properties were determined. The transition dipole moments between two electronic states and Franck-Condon factors of some transitions were evaluated. The spin-orbit coupling effect on the spectroscopic parameters of the X2Π and A2Π states was discussed. The spectroscopic parameters and vibrational properties reported in this paper can be expected to be reliably predicted ones.