Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 5: Glasses and Glass Transition I (joint session DY/CPP)
CPP 5.9: Vortrag
Montag, 11. März 2013, 17:15–17:30, H34
Re-establishment of the equipartition theorem for small systems in molecular dynamics ensemble — •Nima Hamidi Siboni1,2, Dierk Raabe2, and Fathollah Varnik3 — 1AICES, RWTH-Aachen, Germany — 2Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany — 3ICAMS, Ruhr-Universität Bochum, Germany.
It has been reported recently that, in molecular dynamics (MD) simulations, periodic boundary condition leads to a violation of the equipartition theorem for systems containing particles with different masses [Shirts et al, J. Chem. Phys. 125 164102 (2006)]. This effect is associated with the finite number of particles in MD simulations. Here, we propose a modification to MD simulation, which removes this problem. Our method is based on imposing Gaussian random fluctuations on the system’s center of mass velocity. Using the analogy to a system exchanging momenta with impenetrable walls, we work out an analytical expression for the rate at which fluctuations are added to the system. The restoration of the equipartition is then demonstrated for small systems both at equilibrium as well as beyond equilibrium in the linear response regime.