ELECTRONIC-PROPERTIES OF TUBULE FORMS OF HEXAGONAL BC3

First-principles and tight-binding electronic-structure calculations of hypothetical tubule forms of hexagonal BC3 have been performed. According to the total-energy and force calculations, stable atomic geometries of the BC3 tubules can be obtained by rolling hexagonal BC3 sheets keeping the CC and CB lengths at 1.42 and 1.55, respectively. Since the energy increase upon tubule formation is smaller than that of carbon tubules, we conclude that the BC3 tubules are likely to form. The planar BC3 sheet has and * bands above the Fermi level, and this feature is retained in the electronic structures of the BC3 tubules. The influence of concentric formations of the BC3 tubules on their conductivities is also discussed. © 1994 The American Physical Society.