Energetics, structure, and long-range interaction of vacancy-type defects in carbon nanotubes: Atomistic simulations

The presence of vacancy clusters in carbon nanotubes has been assumed to explain the formation of carbon peapods and the difference between the experimentally measured and theoretical fracture strength of nanotubes. We use atomistic simulations at various levels of theory to study the characteristics of large vacancies formed by up to six missing atoms. We show that the formation of big holes on nanotube walls is energetically unfavorable as the vacancies tend to split into smaller defects due to the reconstruction of the nanotube atomic network. We also demonstrate that there is a weak but long-ranged interaction between the vacancies not only through strain fields but, surprisingly, also due to electronic effects, similar to those of adatoms on metal surfaces.