The electronic and structural properties of a single-walled C nanotube under mechanical deformation were studied using first-principles calculations based upon density functional theory. A force was applied over one particular C-atom with enough strength to break the chemical bonds between the atom and its nearest neighbors, leading to a final configuration represented by one tube with a vacancy and an isolated C-atom inside the tube. The investigation demonstrated that there was a tendency for the first bond to break to be the one which was as parallel as possible to the tube axis. Thereafter, the remaining two other bonds were broken. Analysis of the electronic charge densities, just before and after the bonds broke, helped to clarify how the vacancy was formed on an atom-by-atom basis. In particular, for tubes with a diameter of around 11 angstroms, it was shown that the chemical bonds started to break only when the externally applied force was of the order of 14nN; independently of the chirality. The formation energies for the vacancies created using this process were almost independent of the chirality, otherwise the bonds broken and the reconstruction were dependent.

Vacancy Formation Process in Carbon Nanotubes - First-Principles Approach. J.Rossato, R.J.Baierle, A.Fazzio, R.Mota: Nano Letters, 2005, 5[1], 197-200