Nonequilibrium Green's Function Approach to Phonon Transport in Defective Carbon Nanotubes

TL;DR

This paper introduces a nonequilibrium Green's function formalism for phonon transport in nanostructures and applies it to defective carbon nanotubes, revealing how defects influence thermal conductance across temperature regimes.

Contribution

A novel theoretical approach using nonequilibrium phonon Green's functions to analyze phonon transport in defective nanostructures, highlighting defect effects on thermal conductance.

Findings

Universal quantization of low-temperature conductance persists despite defects.

Defects significantly reduce thermal conductance at room temperature.

Transition from quantum to classical transport behavior with increasing temperature.

Abstract

We have developed a new theoretical formalism for phonon transport in nanostructures using the nonequilibrium phonon Green's function technique and have applied it to thermal conduction in defective carbon nanotubes. The universal quantization of low-temperature thermal conductance in carbon nanotubes can be observed even in the presence of local structural defects such as vacancies and Stone-Wales defects, since the long wavelength acoustic phonons are not scattered by local defects. At room temperature, however, thermal conductance is critically affected by defect scattering since incident phonons are scattered by localized phonons around the defects. We find a remarkable change from quantum to classical features for the thermal transport through defective CNTs with increasing temperature.