Extensive spectroscopic calculations of the 21 Λ-S and 74 Ω states of the AsN molecule including the spin–orbit coupling effect

Abstract

The potential energy curves (PECs) of 74 Ω states generated from the 21 Λ-S states of AsN molecule are studied for the first time for internuclear separations from 0.1 to 1.0nm. Of these 21 Λ-S states, the X1Σ+, a′3Σ+, 15Σ+, 13Δ, 13Σ−, a3Π, 15Π, 25Σ+, 35Σ+, 23Δ, 23Π, 33Π, 35Π, and A1Π states are found to be bound, and the 23Σ+, 33Σ+, 15Σ−, 15Δ, 25Δ, 25Π, and 17Σ+ states are found to be repulsive ones. The 33Π state possesses the double well. The 25Σ+, 35Σ+, 35Π, and 33Π states possess the shallow well. The a′3Σ+, 13Σ−, 23Π, 13Δ, 15Π, 25Π, 35Π, and 17Σ+ states are found to be the inverted ones with the spin–orbit coupling effect taken into account. The PECs are calculated using the CASSCF method, which is followed by the internally contracted MRCI approach with Davidson correction. Core–valence correlation and scalar relativistic corrections are included. The vibrational properties are evaluated for the 25Σ+, 35Σ+, and 35Π states and the second well of the 33Π state. The spin–orbit coupling effect is accounted for by the state interaction method with the Breit–Pauli Hamiltonian. The PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are evaluated, and compared with available measurements and other theoretical results. The Franck–Condon factors and radiative lifetimes of the transitions from the a′3Σ+1, a3Π1, A1Π1, 13Δ1 and a3Π0− states to the X1Σ+0+ state are calculated for several low vibrational levels, and some necessary discussion is performed. Analyses show that the spectroscopic parameters reported in this paper can be expected to be reliably predicted ones.