Tight-binding calculations were made of the formation energies of a topological defect, 5-77-5, in achiral carbon nanotubes. The calculations showed that the defect formation energy was dependent upon the chirality and radius of a tube as well as upon the various orientations of the 5-77-5 defect in a tube. Also presented were trends in the defect formation energy, which varied with tube size over the whole size range of the achiral carbon nanotubes. It was found that a positive bond length deviation originating from a 5-77-5 defect in a tube could improve the sp2-like hybridization towards sp2 hybridization locally; which enhanced the stability of the system.

Formation Energies of Topological Defects in Carbon Nanotubes. B.C.Pan, W.S.Yang, J.Yang: Physical Review B, 2000, 62[19], 12652-5