An extended line defect such as a stacking fault was shown to lead to the construction of nanotubes, having fractional indices of chirality, which exhibited interesting electronic structures. Line defects in a 2D lattice were considered; described as a relative displacement of the two halves of the lattice separated by the line and accompanied by selective removal of some atoms located on the line. The results showed that relaxation of graphene sheet with a growth fault, and unit-cell doubling along the fault line, led to a significant lowering of the energy of the fault. It was also found that the radial breathing mode of carbon nanotubes was more strongly dependent upon the diameter than was those of G-band-like modes. Line defects in carbon nanotubes, in the form of edge-sharing pentagon pairs and adjacent octagons, was found to break the symmetry of an ideal nanotube.

Carbon Nanotubes with an Extended Line Defect. M.U.Kahaly, S.P.Singh, U.V.Waghmare: Small, 2008, 4[12], 2209-13