Computing the thermal transport coefficient of neutral amorphous polymers using exact vibrational density of states: Comparison with experiments
Debashish Mukherji
Abstract
Thermal transport coefficient $\ensuremath{\kappa}$ is an important property that often dictates broad applications of a polymeric material, while at the same time its computation remains challenging. In particular, classical simulations overestimate the measurements of $\ensuremath{\kappa}$ in comparison to those of the experiments and thus hinder their meaningful comparison. This is even when very careful simulations are performed using the most accurate empirical potentials. A key reason for such a discrepancy is because polymers have quantum-mechanical, nuclear degrees of freedom whose contribution to the heat balance is nontrivial. In this work, two semianalytical approaches are considered to accurately compute $\ensuremath{\kappa}$ by using the exact vibrational density of states $g(\ensuremath{\nu})$. The first approach is based within the framework of the minimum thermal conductivity model, while the second uses computed quantum heat capacity to scale $\ensuremath{\kappa}$. The computed $\ensuremath{\kappa}$ of a set of commodity polymers compares quantitatively with ${\ensuremath{\kappa}}^{\mathrm{expt}}$.