Characterization of Heat Conduction of Carbon Nanotube by Molecular Dynamics Method

We have been studying the heat conduction along a single-walled carbon nanotube (SWNT) by the molecular dynamics method [1-3] with the simplified form [4] of Tersoff-Brenner bond order potential [5]. Our preliminary results showed that thermal conductivity was strongly dependent on the nanotube length for realistic length scale for device applications [2, 3]. Furthermore, we have reported the direct calculation of phonon dispersion relations and phonon density of states from molecular dynamics trajectories [2, 3]. The calculated thermal conductivity for finite length nanotube was not as high as the previously reported result that it might be as high as 6600 W/mK at 300 K [6]. However, the thermal conductivity was much higher than high-thermal conductivity metals. In order to study the distinctive behavior of heat conduction of carbon nanotubes, several practical molecular dynamics simulations were performed. One example of the interesting feature is the thermal boundary resistance at the junction of nanotubes with different chiralities. The simulation system is shown in Fig. 1. In this case a (12, 0) zigzag nanotube in the left-hand side and a (6, 6) armchair nanotube were smoothly connected using 5-membered and 7-membered rings at the junction. By applying different temperatures at each end, temperature distribution was measured as in Fig. 3. The temperature jump at the junction is very clear. This thermal boundary resistance is quite realistic and also theoretically accessible by the molecular dynamics simulation. Compared with the junction system, a nanotube with a vacancy of a carbon atom did not have much thermal resistance at the defect point. It can be easily speculated that the difference of phonon structures in both sides was quite –200 0 200 290 300 310