Thermal conduction of carbon nanotubes using molecular dynamics

TL;DR

This study uses equilibrium molecular dynamics to analyze how the thermal conductance of carbon nanotubes varies with length, revealing divergence due to low-frequency vibrational modes.

Contribution

It introduces the use of thermal conductance instead of conductivity for CNTs and clarifies the divergence behavior with length through vibrational analysis.

Findings

Thermal conductance diverges with CNT length.

Longer CNTs have more low-frequency vibrational modes.

Vibrational modes contribute to thermal conductance divergence.

Abstract

The heat flux autocorrelation functions of carbon nanotubes (CNTs) with different radius and lengths is calculated using equilibrium molecular dynamics. The thermal conductance of CNTs is also calculated using the Green-Kubo relation from the linear response theory. By pointing out the ambiguity in the cross section definition of single wall CNTs, we use the thermal conductance instead of conductivity in calculations and discussions. We find that the thermal conductance of CNTs diverges with the CNT length. After the analysis of vibrational density of states, it can be concluded that more low frequency vibration modes exist in longer CNTs, and they effectively contribute to the divergence of thermal conductance.