A generalized heat flow algorithm

Abstract

The homogeneous non-equilibrium molecular dynamics (NEMD) heat flow algorithm due to Evans is known to be unstable for large systems (N ⩾ 896) at sufficiently large values of the applied heat field. Instead of heat being conducted homogeneously through the system, the system transfers heat by generating a solitary supersonic shock wave. As a result the effective thermal conductivity increases dramatically. This instability reduces the usefulness of the heat flow NEMD algorithm by increasing the difficulty of making the zero field extrapolation. This extrapolation is necessary in order to calculate the Navier-Stokes thermal conductivity. We present an algorithm which strongly inhibits the generation of the shock wave and results in a conductivity which is largely independent of system size allowing a more efficient extrapolation to zero field.