Electrical and Mechanical Properties of Twisted Carbon Nanotubes

TL;DR

This paper investigates how twisting carbon nanotubes affects their electronic and electrical properties, revealing significant structural and electronic changes with potential implications for nanotechnology applications.

Contribution

It provides a detailed analysis of the energies, structural transitions, and electronic effects of twisting on carbon nanotubes, including transport properties using the Landauer-Büttiker formalism.

Findings

Twisting induces a band-gap in metallic nanotubes.

Structural relaxation significantly influences energy and electronic properties.

Electrical transport varies with nanotube distortion.

Abstract

We have evaluated the energies required to twist carbon nanotubes (NTs), and investigated the effects of these distortions on their electronic structure and electrical properties. The computed distortion energies are high, indicating that it is unlikely that extensive twisting is the result of thermal excitation. Twisting strongly affects the electronic structure of NTs. Normally metallic armchair $(n,n)$ NTs develop a band-gap which initially scales linearly with twisting angle and then reaches a constant value. This saturation is associated with a structural transition to a flattened helical structure. The values of the twisting energy and of the band-gap are strongly affected by allowing structural relaxation in the twisted structures. Finally, we have used the Landauer-B{\"u}ttiker formalism to calculate the electrical transport of the metal-NT-metal system as a function of the NT distortion.