Spin-orbit effects in the ground X2Π state and two low-lying excited valence states B2Π and L′2Φ for NO

Abstract

The potential energy curves and spectroscopic constants B e , ω e , ω e χ e , α e , D e of the six Ω states (X 2Π1/2, 3/2, B 2Π1/2, 3/2 and L ′2Φ5/2, 7/2) of the NO radical molecule were calculated using spin-orbit multi-configuration quasi-degenerate perturbation theory (SO-MCQDPT). The spin-orbit coupling effect was considered via the state interaction approach with the full Breit-Pauli Hamiltonian. The spin-orbit splitting energy between the X 2Π1/2 and X 2Π3/2 states of the NO radical is 129.61 cm-1, which agrees reasonably well with the experimental value of 123.13 cm-1. For the B 2Π1/2, 3/2 states, the spin-orbit coupling (SOC) splitting energy is 35.99 cm-1, the corresponding experimental value is 31.7 cm-1. The SOC splitting value of the L ′2Φ5/2, 7/2 states was calculated to be 103.2 cm-1. The spectroscopic constants R e , ω e , ω e χ e , B e , α e , D e are in reasonable agreement with available experimental and theoretical data for the six Ω states.