Size-dependent electronic structures of boron carbonitride (BC2N) nanotubes. A DFT approach

The electronic structures and physical properties of zigzag BC2N (n,0; n = 4-10) and armchair BC2N (n,m; n = m = 4-10) nanotubes (type Ill) are studied by using density functional theory with the generalized gradient approximation. From a comparison of the binding energies, it is inferred that in the large diameter BC2N nanotubes, the zigzag form is thermally more stable than the armchair form. BC2N nanotubes (with the exception of (4,0) which is conductor) are gapless semiconductors. Depend on the chirality index, the zigzag forms of BC2N nanotubes have narrower band gap than the armchair form. Semiconductor character in the studied BC2N nanotubes is due to contribution of p electrons in the Fermi level. Mulliken population analyses show that significant amounts of electron charge are transferred between atoms; which suggests the existence of polar covalent bonds in the BC2N nanotubes. (C) 2011 Elsevier Ltd. All rights reserved.