Channelling Ions

摘要: In this chapter we examine the results of simulations of ion channelling at kinetic energies of up to 1.3 MeV in our tight-binding model metal. Our explicit treatment of both the ionic positions and of the electronic system allows new features to emerge that are not predicted by simpler models employing a spatially invariant stopping medium. So, whilst we find that at velocities of less than 6 Å fs−1 the stopping power is proportional to velocity, we also find a suppression of the stopping power at higher speeds. This suppression is significant and becomes very large when high values of the on-site charge self consistency parameter U are employed. We also find a resonant enhancement of the steady state average charge on the channelling ion over a well-defined range of velocities. We explain all of our results within a tight-binding picture of bonds between neighbouring atoms and using perturbation theory …