Effective shear-strain driven electromechanical response in helical rippled carbon nanotubes

Abstract

Although objective molecular dynamics coupled with symmetry-adapted tight binding allows for a rigorous atomistic description of helical rippling [D.-B. Zhang, R. D. James, and T. Dumitric\ifmmode \u{a}\else \u{a}\fi{}, Phys. Rev. B 80, 115418 (2009)], there is still little understanding about what effect drives the observed changes in electronic structure. We show that the intralayer shear strain, rather than the known bilayer coupling and $\ensuremath{\sigma}\text{\ensuremath{-}}\ensuremath{\pi}$ orbital mixing effects, dominates gapping in armchair carbon nanotubes. Using an effective shear strain of the tube wall, we relate the response of the rippled morphology to the known behavior exhibited by cylindrical carbon nanotubes.