A direct method to calculate thermal conductivity and its application in solid HMX

The calculation of thermal conductivity for complex material systems is a challenging problem in computational materials science. Its key point is to calculate heat flux. In this work, we derive a concise formula for this purpose based on the equation of motion and then use it to study the thermal conduction properties of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), which is a widely used plastic-bonded explosive (PBX). The results are in fair agreement with experiments and show a distinct thermal conduction anisotropy for HMX single crystals. Then we investigate some key issues of thermal conductivity, such as its temperature-dependence and composition-dependence. A series of interesting results are obtained.