Curvature and chirality dependence of the properties of point defects in nanotubes

This article presents a systematic study of how point defects, such as SW-defects and vacancies, influence the properties of nanotubes. The DFT calculations show that large atomic relaxations at vacancies leads to a contraction of the nanotube. The formation energy E-form, has a curvature, chirality and a family dependence, where E-form is slightly lower in metallic compared to semiconducting nanotubes. The vacancies become electrically active due to defect states close to epsilon(f) and its population depend on the chirality and the position of epsilon(f). A model based on the heat of formation of defective nanotubes furthermore provide an upper estimate for the defect concentration, which is in better agreement with values from AFM experiments than the standard equilibrium approximation. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.