Scale-Bridging Thermodynamic and Kinetic Simulation (STKS)
Maintaining the equipartition theorem in small heterogeneous molecular dynamics ensembles
N. H. Siboni, D. Raabe, F. Varnik.
Physical Review E, The American Physical Society, 87, 030101, (2013)
It has been reported recently that the equipartition theorem is violated in molecular dynamics simulations with periodic boundary condition [R. B. Shirts et al., J. Chem. Phys. 125, 164102 (2006)]. This effect is associated with the conservation of the total momentum. Here, we propose a fluctuating center of mass molecular dynamics approach to solve this problem. Using the analogy to a system exchanging momentum with its surroundings, we work out—and validate via simulations—an expression for the rate at which fluctuations shall be added to the system. It is shown that the proposed method maintains equipartition both at equilibrium and beyond equilibrium in the linear response regime.