The geometries, formation energies and electronic band structures of (8,0) and (14,0) single-walled carbon nanotubes with various defects, including vacancy, Stone-Wales defect, and octagon-pentagon pair defects, were investigated within the framework of density-functional theory. The influence of the concentration of the same type of defect upon the physical and chemical properties of single-walled carbon nanotubes was also studied. The results suggested that the existence of vacancy and octagon-pentagon pair defects both reduced the band gap, whereas the Stone-Wales defect introduced a band-gap opening in carbon nanotubes. The band gaps of (8,0) and (14,0) single-walled carbon nanotube configurations, with two octagon-pentagon pair defects, were 0.517 and 0.163eV; these were a little smaller than for perfect carbon nanotubes. With increasing concentration of defects, there was a decrease in the band gap; making the two types of single-walled carbon nanotube change from semiconductors to metallic conductors.

Effects of Various Defects on the Electronic Properties of Single-Walled Carbon Nanotubes: a First Principle Study. Q.X.Zhou, C.Y.Wang, Z.B.Fu, Y.J.Tang, H.Zhang: Frontiers of Physics, 2014, 9[2], 200-9