We use molecular dynamics simulations to study the thermal transport properties of a range of poor to good thermal conductors by a method in which two portions are delimited and heated at two different temperatures before the approach-to-equilibrium in the whole structure is monitored. The numerical results are compared to the corresponding solution of the heat equation. Based on this comparison, the observed exponential decay of the temperature difference is interpreted and used to extract the thermal conductivity of homogeneous materials. The method is first applied to bulk silicon and an excellent agreement with previous calculations is obtained. Finally, we predict the thermal conductivity of germanium and a-quartz. V

We use molecular dynamics simulations to study the heat transfer at the interface between crystalline Si and amorphous silica. In order to quantify the thermal boundary resistance, we compare the results of two simulation methods: one in which we apply a stationary thermal gradient across the interface, trying to extract the thermal resistance from the temperature jump; the other based on the exponential approach to thermal equilibrium, by monitoring the relaxation times of the heat flux exchanged across the interface. We compare crystalline Si/amorphous Si vs. crystalline Si/amorphous silica interfaces to assess the relative importance of structural disordering vs. chemistry difference.