Investigation of The Electronic Properties of Single Wall Carbon Nanotube SWCNT (7,0) using Density Functional Theory (DFT)

In this paper electron features for zigzag carbon nanotubes SWCNT7,0 were studied. Using Density Functional Theory DFT and calculating Cohen-Scheme many body equations with Self Consistent Field SCF approach and considering Local Density Approximation LDA, the investigation was performed. The nanotube´s morphology is cylindrical with cross section of 5.480 Å and growing in 100 direction. After calculating energy convergence, the cutoff energy of 953 eV was selected and the inverse space was meshed as 1×1×16 by Monkhorst-Pack method. Results showed that the nanotube´s energy gap was Reduces due to high surface to volume ratio and creating surface levels within the gap. Furthermore, electron properties including band structure and electron states densities were calculated for SWCNT7,0 and it was found that maximum valance band and minimum conduction band were both at Г point. These two bands are stemmed from bonding level of π and antibonding level of π with energies of -0.53 eV and 0.62 eV, respectively from Fermi level. Therefore, a direct energy gap of 1.15 eV was created at Г point and as was expected the nanotube was placed among semiconductor materials. In addition, the valance and conduction bandwidths calculated between Г and Z points were 1.92 eV and 2.23 eV, respectively. Thus, self-interaction error has no significant effect on results.