Floquet theory for the electronic stopping of projectiles in solids

A theoretical framework for the study of electronic stopping of particle projectiles in crystalline solids is proposed. It neither relies on perturbative or linear-response approximations nor on an ideal metal host. Instead, it exploits the discrete translational invariance in a space-time diagonal for a constant velocity projectile following a trajectory with crystalline periodicity. By means of Floquet theory, (stroboscopically) stationary solutions are characterized, and previous perturbative and jellium models are recovered. The threshold-velocity effect in insulators is analyzed based on quasienergy conservation.