A mesodynamic method, dynamics with implicit degrees of freedom, was used to characterize thermal transport in a model molecular crystal above and below its melting point. The method represented groups of atoms (molecules in this case) using mesoparticles and the thermal role of the intramolecular degrees of freedom were described implicitly using their specific heat. Attention was focussed on the role of these intramolecular degrees of freedom in thermal transport. It was found that thermal conductivity was independent of intramolecular specific heat for solid samples and a linear relationship between the two quantities in liquid samples with the coefficient of proportionality being the mass diffusivity of the mesoparticles. As the temperature of the liquids was increased, thermal conductivity exhibited an increased sensitivity with respect to the specific heat of the internal degrees of freedom due to the enhanced molecular mobility. Based upon these results, a simple method was proposed for incorporating quantum corrections to the thermal conductivity obtained from non-equilibrium molecular dynamics simulations of molecular liquids.

Thermal Conduction in Molecular Materials using Coarse Grain Dynamics: Role of Mass Diffusion and Quantum Corrections for Molecular Dynamics Simulations. Zhou, Y., Strachan, A.: Journal of Chemical Physics, 2009, 131[23], 234113