Structural phase transition and band gap of uniaxially deformed (6,0) carbon nanotube

TL;DR

This study investigates how uniaxial elongation affects the atomic structure and electronic band gap of a (6,0) zigzag carbon nanotube, revealing a phase transition and changes in its semiconducting properties.

Contribution

It provides the first detailed analysis of the structural phase transition and band gap evolution in a (6,0) carbon nanotube under axial strain using semiempirical and tight-binding methods.

Findings

Structural phase transition at ~9% elongation from Kekule to quinoid structure.

Transition from a narrow to a moderate band gap semiconductor.

Validation of semiempirical PM3 method for nanotube analysis.

Abstract

The atomic and band structures of the (6,0) zigzag carbon nanotube at its axial elongation are calculated by semiempirical molecular orbital and by tight-binding methods. The ground state of the nanotube is found to have a Kekule structure with four types of bonds and difference between lengths of long and short bonds of about 0.005 nm. The structural phase transition is revealed at ~9% elongation, resulting in a quinoid structure with two types of bonds. This structural phase transition is followed by the transition from a narrow gap to moderate gap semiconductor. Validity of the semiempirical PM3 method is discussed.