Pressure, temperature, and orientation dependent thermal conductivity of pentaerythritol tetranitrate (PETN)

Abstract

We use reverse non-equilibrium molecular dynamics to determine the thermal conductivity tensor, κ, of tetragonal pentaerythritol tetranitrate (PETN). The most stable form under standard ambient conditions (PETN I, with space group P4¯21c) is considered in the temperature and pressure intervals 200–500 K and 0–8 GPa, which covers approximately the stability range for this polymorph. We compute κ along the [100] and [001] directions, which is enough to construct the full thermal conductivity tensor for a system with tetragonal symmetry. In addition, we also determine κ along the [010] direction and confirm that κ100∼κ010, with less than 4% average absolute error between the two quantities. We observe an anisotropic response for κ, with κ100>κ001 across the whole (T,P) interval, and 37% difference at 300 K, 0 GPa. We provide analytical functions to interpolate κ(P,T) within the fitting interval and serve as input for continuum-scale simulations.