The heat flux autocorrelation functions of carbon nanotubes (CNT’s) with different radii and lengths are calculated using equilibrium molecular dynamics with periodic boundary conditions. The thermal conductance of CNT’s is also calculated using the Green-Kubo formula from linear response theory. By pointing out an ambiguity in the cross-section definition of single-wall CNT’s, we refer to the thermal conductance instead of conductivity in calculations and discussions. We find that the thermal conductance of CNT’s diverges with the length of CNT’s. After an analysis of vibrational density of states, it is shown that there are more and stronger low-frequency vibrational modes in longer CNT’s, and these modes effectively contribute to the divergence of thermal conductance.

• Received 29 December 2003

DOI:https://doi.org/10.1103/PhysRevB.71.085417