The characteristics of 5–7 pair couple defects formed in single-walled C 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 the bending deformation of the nanotubes due to the defects. The resulting stable structure was found to change with the number of atoms removed, showing a bending angle of 16.6° for a diameter of 10.7Å. The dependence of bending angle on the diameter of nanotubes was analysed using a simple model. As results, several sets of 5–7 pair couple defects were found to be necessary in order to induce plastic deformation that was experimentally observed in nanotubes.

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