Theoretical studies of the electronic spectrum of SnSe

Multireference configuration interaction calculations are performed on the SnSe molecule to study its electronic spectrum within 5 eV of energy. Potential energy curves of the ground and low-lying electronic states, which correlate with the lowest dissociation limit, are constructed. Spectroscopic constants (Te, re, ωe) of nine bound states of SnSe are reported. The ground-state dissociation energy is estimated to be 4.38 eV. The spin–orbit interaction has also been included in the calculation. Transition dipole moments of several dipole-allowed and spin-forbidden transitions are computed. Transitions such as E 1 Σ 0 + + – X 1 Σ 0 + + and D 1 Π 1 – X 1 Σ 0 + + are found to be more probable. The radiative lifetimes of A 0 + – X 1 Σ 0 + + and B 1 – X 1 Σ 0 + + are predicted to be about 11 and 130 μs, respectively. Dipole moments of the ground and low-lying states are estimated and compared with observed data.