Extensive ab initio calculation on low-lying excited states of SiN+ cation including spin-orbit coupling

Abstract

Electronic structures and transition properties of the SiN+ molecule are investigated by performing ab initio calculations based on scalar relativistic multireference configuration interaction (MRCI) method plus Davidson correction (+Q). The potential energy curves (PECs) for the 22 Λ-S electronic states of the SiN+ are obtained. The spectroscopic constants of the bound states are determined, where good agreements with the available spectroscopic data are achieved. Spin-orbit coupling (SOC) effect is introduced via the state interaction approach with the full Breit-Pauli Hamiltonian operator for the state X3 Σ −, a 3 Π, 5 Σ − and 5 Π. This is the first time that SOC calculation has been carried out on the SiN+. The four states split into 15 Ω states after the consideration of the SOC effect. The SOC effect, leading to some avoided crossings, is found to be substantial for the SiN+. Moreover, the transition dipole moments (TDMs) and Franck-Condon factors are derived. Finally, the corresponding radiative lifetimes of the a 3 Π 1 state are evaluated.