Ab Initio Prediction of Spectroscopic Constants of MgN in X 4Σ- AND a 2Π Electronic States: Another Potential Candidate for a New Mg-bearing Interstellar Molecule

Spectroscopic constants for the lowest ⁴Σ^- and ²Π states of the MgN radical have been calculated by the multireference singles and doubles configuration interaction method, including Davidson's correction for quadruple excitations [MR-SDCI(+Q)]. It is shown that the ⁴Σ^- state is the ground state of MgN and that the ²Π state is the first excited state, lying 6.5 kcal mol^-1 higher in energy. The binding energy for the X ⁴Σ^- state is evaluated as 11.1 kcal mol^-1, and the rotational constants are B_e = 13.357 and B₀ = 13.259 GHz. The spectroscopic constants presented here will help in the detection of the MgN radical in interstellar space.