Electronic stopping of ions in the low velocity limit

Abstract

The change in kinetic energy of an ion moving in an equilibrium electron gas is considered as a model for electronic stopping power. The exact small velocity limit is obtained for an ion of infinite mass. It is shown to be linear in the ion speed with a coefficient determined from the autocorrelation function for the force on the ion at rest in the equilibrium electron gas. The result has no limitations with respect to the ion charge, the electron coupling parameter, and the electron degeneracy parameter. Therefore it provides a firm basis for testing various theoretical approximations. Some comments are offered on the semiclassical limit, to provide a model appropriate for study via molecular dynamics simulation.