Electron-phonon interaction within classical molecular dynamics

Abstract

We present a model for nonadiabatic classical molecular dynamics simulations that captures with high accuracy the wave-vector $q$ dependence of the phonon lifetimes, in agreement with quantum mechanics calculations. It is based on a local view of the $e$-ph interaction where individual atom dynamics couples to electrons via a damping term that is obtained as the low-velocity limit of the stopping power of a moving ion in a host. The model is parameter free, as its components are derived from ab initio-type calculations, is readily extended to the case of alloys, and is adequate for large-scale molecular dynamics computer simulations. We also show how this model removes some oversimplifications of the traditional ionic damped dynamics commonly used to describe situations beyond the Born-Oppenheimer approximation.