Molecular Dynamics Simulation of Friction in Xenon Films on a Silver Substrate

We perform molecular dynamics simulations of friction for atomically thin Xe films sliding on Ag(111). We determine the inverse of the coefficient of friction (i.e. slip time) by direct calculation of the decay of the center of mass velocity after applying an external force, as well as from the velocity autocorrelation function. We find that the slip time exhibits a drop followed by a sharp increase in a range of coverage near one monolayer. The slip time then levels off with further coverage increases in agreement with previously reported experiments. Our simulations suggest that the friction found in this system is dominated by phonon excitations.