Uniaxially deformed (5,5) carbon nanotube: Structural transitions

TL;DR

This paper investigates the structural and electronic phase transitions of a (5,5) carbon nanotube under uniaxial tension, revealing a Kekule ground state, Peierls distortions, and a transition from semiconductor to metal.

Contribution

It identifies the Kekule structure and predicts two first-order phase transitions, including a metalization, in a (5,5) nanotube under tension.

Findings

Kekule structure with two bond lengths identified

Structural phase transitions at 5% and 13% elongation predicted

Semiconductor to metal transition at 5% elongation

Abstract

The Kekule structure of the ground state of (5,5) armchair carbon nanotube is revealed by semiempirical molecular orbital calculations. This structure has bonds with two different bond lengths, differing by 0.003 nm. The ground state has tripled (compared to undistorted case) translational period due to Peierls distortions. Two first order structural phase transitions controlled by the tension are predicted at zero temperature. These transitions correspond to 5% and 13% elongations of a uniaxially deformed (5,5) nanotube. The narrow gap semiconductor to metal transition is predicted at 5% elongation of the nanotube.