Curvature and strain effects on electronic properties of single-wall carbon nanotubes

To describe accurately the electronic structures of carbon nanotubes, a semi-empirical tight-binding approach is presented in which the main intrinsic curvatures have been fully taken into account. The calculated electronic structures and band gaps are consistent with experimental measurements. Studies of the relative importance of various intrinsic curvatures show that each curvature has a contribution of varying importance to the curvature-induced band gap. Additionally, under both uniaxial and torsional strain, semiconductor-metal-semiconductor phase transitions have been observed for primary metallic carbon nanotubes. The critical stress of the transition and the gap's sensitivity with stress are dependent on both the diameter and chirality of nanotubes, which is at variance with previous predictions.