Spectroscopic constants and potential energy curves of gallium nitride (GaN) and ions: GaN+ and GaN−

Electronic states of GaN and their ions are studied by employing multi-reference configuration interaction (MRCI) and relativistic DKCCSD(T) calculations. The 3Σ− state is 532 cm−1 below the 3Π state using MRCI, whereas the DKCCSD(T)/CBS energy separation is 857 cm−1. The low lying excited states undergo curve crossing with the dissociative 5Σ− and 5Π states causing predissociation. For GaN−, the ground state is 2Σ+ and an electron affinity of 1.44 ± 0.5 eV with an excited 2Π state at 662 cm−1. GaN+ is weakly bound with an IP of 7.88 eV. The dissociation energy of GaN is 46.5 ± 1 kcal/mol.