The electronic and structural properties of a single-walled C nanotube under mechanical deformation were studied by 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 most parallel to the tube axis. The 2 other remaining bonds were then broken. Analysis of the electronic charge densities, just before and after bond breaking, helped to clarify how the vacancy was formed on an atom-by-atom basis. For tubes with a diameter of around 11Å, it was shown that the chemical bonds started to break only when the externally applied force was of the order of 14nN; independent of chirality. The formation energies for the vacancies created by using this process were almost independent of 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