Electromechanical characterization of carbon nanotubes in torsion via symmetry adapted tight-binding objective molecular dynamics

The nonlinear elastic response of carbon nanotubes (CNTs) in torsion is derived with objective molecular dynamics and a density-functional-based tight-binding model. The critical strain beyond which CNTs behave nonlinearly, the most favorable rippling morphology, and the twist- and morphology-related changes in fundamental band gap are identified from a rigorous atomistic description. There is a sharply contrasting behavior in the electronic response: while in single-walled CNTs the band-gap variations are dominated by rippling, multiwalled CNTs with small cores exhibit an unexpected insensitivity. Results are assistive for experiments performed on CNT-pedal devices.