Structure and Stability of Boron Nitrides: Isomers of B12N12

Abstract

A number of recent studies have explored the energetics of intermediate-sized clusters, such as small fullerenes. For example, the isomer energies of C20 have proven difficult to ascertain as different theoretical methods give widely varying results. For cluster sizes around 20−30 atoms, it is not immediately clear whether a monocyclic, graphitic, or fullerene structure is energetically preferred. In the present work, the isomers of B12N12, a ring, a “graphitic” sheet, and a fullerene-like cage of four- and six-membered rings, are examined by theoretical means. The energies of the three isomers are calculated using Hartree−Fock theory and density functional theory (DFT) in local and gradient-corrected forms. The Dunning correlation-consistent basis sets are used, with geometries optimized up to the triple-ζ level and energies calculated at the quadruple-ζ level. The effects of the basis set, as well as the effects of local versus nonlocal DFT, are discussed. The results are compared to those of similar studies of C24, which is isoelectronic with B12N12.