The characteristics of 5-7 pair couple defects formed in single-walled carbon nanotubes were investigated. For armchair nanotubes with diameters from 6.8 to 13.6Å, such defects were formed by removing atoms. Structural optimization, which was carried out using tight-binding molecular dynamics, resulted in bending deformation of the nanotubes due to the defects. The resultant stable structure was found to change with the number of atoms removed, with a bend angle of 16.6° for a diameter of 10.7Å. The dependence of bend angle upon the diameter of the nanotubes was analyzed using a simple model. Several sets of 5-7 pair couple defects were found to be necessary in order to induce the plastic deformation that was observed experimentally in nanotubes.

Bending Deformation of Single-Walled Carbon Nanotubes Caused by 5-7 Pair Couple Defect. K.Wako, T.Oda, M.Tachibana, K.Kojima: Japanese Journal of Applied Physics – 1, 2008, 47[8-1], 6601-5