Enhancing Molecuar Dynamics to Capture Electronic Effects

In modeling non-equilibrium thermal transport in nanoscale systems, classical molecular dynamics (MD) has the primary strength of explicitly representing phonon modes and scattering mechanisms. On the other hand, electrons and their role in energy transport are missing. Our goal is to couple a MD treatment of the ionic subsystem with a partial differential equation based model of the electronic subsystem in order to accurately capture aggregate behavior at the nanoscale. Along these lines, we have enhanced the LAMMPS MD package by coupling the ionic motions to a finite element based representation of electronic heat transport. The coupling between the subsystems occurs via a local version of the two-temperature model. Key parameters describing the coupling are calculated using Time Dependent Density Functional Theory (TDDFT) calculations with either explicit or implicit energy flow. We will discuss initial demonstrations of our approach focusing on nanowires and carbon nanotubes.