Combining equilibrium and non-equilibrium molecular dynamics simulations with accurate carbon potentials, we determine the thermal conductivity λ of carbon nanotubes and its dependence on temperature. Our results suggest an unusually high value λ≈6, 600 W/m·K for an isolated (10, 10) nanotube at room temperature, comparable to the thermal conductivity of a hypothetical isolated graphene monolayer or diamond. Our results suggest that these high values of λ are associated with the large phonon mean free paths in these systems; substantially lower values are predicted and observed for the basal plane of bulk graphite. 61.48.+c, 66.70.+f, 63.22.+m, 68.70.+w With the continually decreasing size of electronic and micromechanical devices, there is an increasing interest in materials that conduct heat efficiently, thus preventing structural damage. The stiff sp 3 bonds, resulting in a high speed of sound, make monocrystalline diamond one of the best thermal conductors [1]. An unusually high thermal conductance should also be expected in carbon nanotubes [2,3], which are held together by even stronger sp 2 bonds. These systems, consisting of seamless and atomically perfect graphitic cylinders few nanometers in diameter, are self-supporting. The rigidity of these systems, combined with virtual absence of atomic defects or coupling to soft phonon modes of the embedding medium, should make isolated nanotubes very good candidates for efficient thermal conductors. This conjecture has been confirmed by experimental data that are consistent with a very high thermal conductivity for nanotubes [4].In the following, we will present results of molecular dynamics simulations using the Tersoff potential [5], augmented by Van der Waals interactions in graphite, for the temperature dependence of the thermal conductivity of nanotubes and other carbon allotropes. We will show that isolated nanotubes are at least as good heat conductors as high-purity diamond. Our comparison with graphitic carbon shows that inter-layer coupling reduces thermal conductivity of graphite within the basal plane by one order of magnitude with respect to the nanotube value which lies close to that for a hypothetical isolated graphene monolayer.The thermal conductivity λ of a solid along a particular direction, taken here as the z axis, is related to the heat flowing down a long rod with a temperature gradient dT /dz bywhere dQ is the energy transmitted across the area A in the time interval dt. In solids where the phonon contribution to the heat conductance dominates, λ is proportional to Cvl, the product of the heat capacity per unit volume C, the speed of sound v, and the phonon mean free path l. The latter quantity is limited by scattering from sample boundaries (related to grain sizes), point defects, and by umklapp processes. In the experiment, the strong dependence of the thermal conductivity λ on l translates into an unusual sensitivity to isotopic and other atomic defects. This is best illustrated by the reported thermal conductivity values in the ba...

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