Defects in carbon nanotubes

It is a consensus that defects can alter in a significant way the mechanical properties of carbon nanotubes. We here will investigate, using ab initio total energy density functional theory calculations, some defects and their properties, such as: 1) an interstitial carbon atom right besides a vacancy that can connect tubes in bundles or in multiwall nanotubes; 2) two vacancies that can connect tubes in bundles; 3) a variety of configurations for two vacancies in one nanotube, and how their energies vary with separation. In particular, we will compare the formation energies of the 5-8-5 and 555-777 two-vacancy defects as a function of nanotube diameter.