Irradiation effects in single-walled carbon nanotubes: Density-functional theory based treatments

The collision process of a low-energy carbon ion impinging single-walled carbon nanotubes is studied by using a self-consistent-charge density-functional tight-binding molecular dynamics method. The simulation shows that the outcome of the collision highly depends on the incident kinetic energy and the impact location in the nanotube. There are five types of processes observed: adsorption, reflection, substitution, penetration and damage. The adsorption process becomes dominant at energies lower than 20 eV. Defect formation events are observed at energies larger than 20 eV. For this process, 5-1DB, 5-8-5, Stone–Wales, 7-4-5-9-5 and 5-7-7-6-5 defects are obtained. The formation processes of the typical defects are described in detail. Moreover, the energy exchange and the charge transfer between the incident carbon ion and the nanotube have also been quantitatively studied.