A systematic study was made of how point defects, such as SW-defects and vacancies, influenced the properties of nanotubes. The calculations showed that large atomic relaxations at vacancies led to a contraction of the nanotube. The formation energy exhibited a curvature, chirality and family dependence: being slightly lower in metallic, as compared with semiconducting, nanotubes. The vacancies became electrically active due to defect states close to εF, and the population depended upon the chirality and position of εF. A model which was based upon the heat of formation of defective nanotubes provided an upper estimate, on the defect concentration, which was in better agreement with values arising from atomic force microscopy experiments than was the standard equilibrium approximation.

Curvature and Chirality Dependence of the Properties of Point Defects in Nanotubes. J.M.Carlsson: Physica Status Solidi B, 2006, 243[13], 3452-7