Theoretical prediction on HBeN − and HNBe − anions using multiconfiguration second‐order perturbation theory

The HBeN − and HNBe − anions have been investigated for the first time using the CASSCF, CASPT2, and DFT/B3LYP methods with the contracted atomic natural orbital (ANO) and cc‐pVTZ basis sets. The geometries of all stationary points along the potential energy surfaces were optimized at the CASSCF/ANO and B3LYP/cc‐pVTZ levels. The ground and the first excited states of HBeN − are predicted to be X 2 Π and A 2 Σ + states, respectively. It was predicted that the ground state of HNBe − is X 2 Σ + state. The A 2 Π state of HNBe − has unique imaginary frequency. A bend local minimum M1 was found along the 1 2 A″ potential energy surface and the A 2 Π state of HNBe − should be the transition state of the isomerization reactions for M1 ↔ M1. The CASPT2/ANO potential energy curves of isomerization reactions were calculated as a function of HBeN bond angle. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010