An improved model of interatomic forces for large simulations of metals containing excited electrons

Abstract. We derive a form for the non-conservative damping forces on metal ions due to their interactions with electrons, and present the result in the second-moment tight-binding approximation suitable for direct and efficient inclusion in a large-scale molecular dynamics simulation. We demonstrate that this form accurately captures the direction, velocity, temperature and local atomic environment dependence of the non-adiabatic force in quantum mechanical simulations in which electronic stopping is accurately calculated. No previous empirical damping force is able to reproduce this rich behaviour.