Kinetic Energy-Based Temperature Computation in Non-Equilibrium Molecular Dynamics Simulation

The average kinetic energy is widely used to characterize temperature in molecular dynamics (MD) simulation. In this letter, the applicability of three types of average kinetic energy as measures of temperature is investigated, i.e., the total kinetic energy, kinetic energy without the centroid translation part, and thermal disturbance kinetic energy. Our MD simulations indicate that definitions of temperature based on the kinetic energy including rigid translational or rotational motion may yield unrealistic results. In contrast, the thermal disturbance kinetic energy has wider applicability to temperature computation in non-equilibrium molecular dynamics simulation. If small samples need to be used for local temperature, then a calibration approach is proposed to eliminate the sample-size dependence of the average disturbance kinetic energy.