Density-functional study of the mechanical and electronic properties of narrow carbon nanotubes under axial stress

Abstract

The behavior of some narrow single-wall carbon nanotubes under uniaxial stress was studied. The first principles local density-functional calculations were carried out using helical repeat units and periodic boundary conditions for a single infinite chain. The mechanical response of the tube, the geometrical deformations, and the axial elastic modulus are calculated. The mechanical deformations are reflected also in the electronic properties. The change of the band gaps of the chiral tubules under axial stress was investigated. The indirect gaps of $\ensuremath{\sim}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ can be closed applying small $(l5%)$ deformations which results in semiconductor-metal transitions.