Electronic and magnetic properties of deformed and defective single wall carbon nanotubes

The combined effect of radial deformation and defects on the properties of semiconducting single wall carbon nanotubes are studied using density functional theory. A Stone-Thrower-Wales defect, a substitutional nitrogen impurity, and a mono-vacancy at the highest curvature side of a radially strained nanotube are considered. The energies characterizing the deformation and defect formation, the band gap energies, and various bond lengths are calculated. We find that there is magneto-mechanical coupling behavior in the nanotube properties which can be tailored by the degree of radial deformation and the type of defect. The carbon nanotube energetics and magnetism are also explained in terms of electronic structure changes as a function of deformation and types of defects present in the structure. (C) 2009 Elsevier Ltd. All rights reserved.