Lattice defects and boundaries in conducting carbon nanotubes

TL;DR

This paper investigates how various defects and boundary structures affect the electronic properties of conducting carbon nanotubes using an exact lattice model mapping, providing insights relevant for experimental observations.

Contribution

It introduces a general method to incorporate and analyze different imperfections in carbon nanotubes within a simplified lattice framework.

Findings

Electron density patterns for specific defects and caps are predicted.

Impurities like Stone-Wales defects and vacancies significantly alter electronic properties.

The method enables detailed physical interpretation of defect effects.

Abstract

We consider the effect of various defects and boundary structures on the low energy electronic properties in conducting zigzag and armchair carbon nanotubes. The tight binding model of the conduction bands is mapped exactly onto simple lattice models consisting of two uncoupled parallel chains. Imperfections such as impurities, structural defects or caps can be easily included into the effective lattice models, allowing a detailed physical interpretation of their consequences. The method is quite general and can be used to study a wide range of possible imperfections in carbon nanotubes. We obtain the electron density patterns expected from a scanning tunneling microscopy experiment for half fullerene caps and two typical impurities in the bulk of a tube, namely the Stone-Wales defect and a single vacancy.