Structural exploration and properties of (BN)6 cluster via ab initio in combination with particle swarm optimization method

The particle swarm optimization method is used to search for the isomers of (BN)(6) cluster, then the selected possible lower energy isomers are optimized using the DFT. Sixteen configurations that are stable stationary points on the potential energy surface at B3LYP/6-31G (d) level are found. Among the isomers, six of them have been reported and ten new low energy structures are found for the first time. We calculated the geometry optimization, infrared spectrum, relative Gibbs free energy topological analysis and polarizability. The lowest energy structure S1 is found to be the most stable configuration, which agrees with the previous results. By calculating Gibbs free energy, we also get their energy orders at different temperatures. The main interaction between B and N is demonstrated to be covalent by the topological analysis of (BN)(6). Our calculated energy gap and polarizability obey the rule that a cluster with a wide energy gap always has small mean static polarizability.