First-Principle Calculations of Electronic Structure of the (3,3), (4,4), (5,0) and (6,0) Single-Wall Carbon Nanotubes

Abstract

On the basis of density functional theory, we study the electronic structures of (3,3), (4,4), (5, 0) and (6, 0) SWCNTs. The results show that the cohesive energy of armchair tubes are larger than those of zigzag ones. The calculated band gap of (4,4) is smaller than those of other tubes. Moreover, the band gap for armchair tubes are smaller than those of zigzag. The variation of ionization potential, electron affinity, and Fermi energy level as the number of atoms in the tube grows up. This curve fluctuates strongly because of the change in size that produce different surfaces with different properties. The IP is larger than the EA, as is the normal situation for molecules. The highest number of degenerate states in the conduction and valence bands are about as follow: 7, 9, 9, and 7 for (3,3), (4,4), (5,0) and (6,0) CNTs, respectively.

Keywords: DFT, electronic structure, single-wall carbon nanotubes