Ab-initio study of the spectroscopy, kinetics, and thermochemistry of the bn2 molecule

Abstract

Several low-lying structures and electronic states of the BN2 molecule have been studied using complete active space SCF, multireference averaged coupled-pair functional (ACPF), and coupled-cluster (CCSD(T)) methods. BNN(2PI) and BN2(2A1) are very close together in energy: at the ACPF level, the separation is 2.8 kcal/mol. The potential surface for the transition between these structures appears to have a significant energy barrier, so it is surprising that the 2A1 state has not yet been observed. Conversely, the low-lying BN2(2B2) state has a very low barrier towards dissociation, which explains why it has not been observed. The symmetric linear species NBN(2PI), on the other hand, is substantially higher in energy, but has a very large barrier towards dissociation and is therefore observed experimentally. At our highest level of theory, the ground BNN(2PI) state is nearly isoenergetic with B(2P)+N2(X 1SIGMA+).