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

      The velocities of atoms in MD simulation are not objective quantities, which depend on the choice of the reference frame and sample size. In our previous study (node/3181), we discussed how to overcome this non-objectivity and compute the atomic stress objectively. In this blog, our newly published paper on temperature computation is attached, and the abstract is as follows.

A kinetic energy-based approach is developed to obtain the correct local temperature of nonequilibrium systems. We have demonstrated that as a temperature measure, the average disturbance kinetic energy of a sample is more applicable than its average total energy, and the latter has been widely used in most molecular dynamics software. However, it is proved and demonstrated by our simulation example that the average disturbance kinetic energy is sample-size dependent. By using a simple equilibrium system as a thermometer, we propose a calibration approach to eliminate this sample-size effect. A vibrating atomic bar is used as an example to test the validity and convergence of various temperature definitions.