The electronic structure of carbon nanotubes containing defects was investigated within a tight-binding framework. The electronic properties of the following defects were examined: a hemispherical cap ending a (10,10) tubule, a pentagon - heptagon pair aligned along the same side of the tube, which widened the diameter, a diametrically-opposed heptagon - pentagon pair, which bent the structure, and sp3-like lines responsible for polygonization. In the first 3 cases, structural optimization was performed by minimization of a valence-force field adapted to the carbon network, or by tight-binding molecular dynamics.

Electronic Properties of Carbon Nanotubes Containing Defects. P.Lambin, A.A.Lucas, J.C.Charlier: Journal of Physics and Chemistry of Solids, 1997, 58[11], 1833-7