The low-lying electronic states of the GaN molecule

High-level multireference calculations are reported for the low-lying electronic states of GaN. Using the CASSCF/MRSDCI approach and the aug-cc-pVQZ basis set a detailed analysis is given for the 22 electronic states that dissociate in the first two channels. The ground state is confirmed as (X3Σ−) but the first excited state ((1)3Π) is found to be very close in energy. A very accurate spectroscopic characterization is made for the lowest-lying triplet and singlet states. The behavior of dipole moment and transition dipole moment with internuclear distance is also described. Relative intensities are predicted using the Einstein coefficients.