Abstract: The structures and stabilities of twenty- three B28N28 alternant structures have been investigated at the B3LYP/6- 31G* level of density functional theory. It is found that stability index of all the isomers obey a simple N4x4(x=0, 1, 2) topological rule characterizing the number of bonds between squares. The relative energies show an increasing tendency with the rising of x in N4x4(x=0, 1, 2), in which N404 is dominant. The present study provides a simple topological criterion that can be used to sort an approximate stability order of all the isomers and select the more stable candidate from the ISR(isolated square rule) structures. The simple filtering scheme is ideally suited for prescreening the thermodynamically viable structures of large boron nitride clusters.

Key words: Boron nitride, Stability, Topology, Density functional theory