Molecular dynamics simulations of thermal transport in metals using a two-temperature model.

Abstract

Context: In classical molecular dynamics, thermal transport via electrons is typically non-existent. Therefore, thermal property determination in metals or material systems that include metals is inaccessible. We have developed a two-temperature model for use with non-equilibrium molecular dynamics to predict thermal interface resistance across metal-metal and metal-insulator interfaces. Using LAMMPS and a modified module for the diffusion of thermal energy via electrons, we systematically examine the effects of including a second transport pathway through material systems. We found that inclusion of an electronic transport pathway reduces the phonon-only thermal conductivity because of electron-phonon scattering. Moreover, the presence of electrons eliminates temperature jumps at the boundary but still admits interface resistance, which is reduced in some cases by an order of magnitude.

Method: We developed a module for LAMMPS that estimates thermal transport via the diffusion equation with a specified electron thermal conductivity. The electronic energy is transferred to/from the atomic system using velocity rescaling with appropriate momentum perturbation. The atomistic motion is governed by the NiU3-EAM potential.