ELECTRONIC STOPPING OF IONS IN THE LOW-VELOCITY LIMIT

The change in kinetic energy of an ion moving in an equilibrium electr on gas is considered as a model for electronic stopping power. The exa ct 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 fro m 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 d egeneracy parameter. Therefore it provides a firm basis for testing va rious theoretical approximations. Some comments are offered on the sem iclassical limit, to provide a model appropriate for study via molecul ar dynamics simulation.