The Electronic Drag Force

摘要: In this chapter we return to our study of non-adiabatic effects on the forces in collision cascades. In this case we examine the behaviour of the non-adiabatic force on the moving ions. Various attempts have been made to capture the effects of such forces in classical MD simulations by adding a drag force to the ionic dynamics. Our time-dependent tight-binding simulations give us direct access to information about these forces and so we use a set of cascade simulations to assess the validity of simple drag models. By considering the origin of the non-adiabatic force within a tight-binding picture we are able to propose a new classical model for the non-adiabatic force; one which can be easily incorporated within a classical MD scheme at near zero computational cost. We evaluate the performance of our model using simulation data and find that it is a significant improvement over simple damping models. In …