PhD Thesis Defense: Electron dynamics in out of equilibrium systems from real-time time-dependent density functional theory

This Thesis investigates nonequilibrium electronic dynamics using real-time time-dependent density functional theory (rt-TDDFT), a first-principles method that describes the time evolution of many-electron systems beyond linear response. This study addresses three problems related to electronic energy transfer in moving systems. First, it examines the electronic stopping power of electron projectiles in bulk lithium fluoride (LiF) and liquid water. It introduces a method that considers the finite mass of the projectile, non-linear electronic response, and scattering with target ions. Second, the work analyzes the response of quantum many-body systems to the sudden onset of motion of a local external potential, what we call a quantum kick. This analysis reveals countercurrents related to the Drude weight in metals and strong nonlinear effects in insulators. Third, it examines the electronic energy transfer between two graphene layers in vacuum through rt-TDDFT and Floquet theory, showing that the breaking of translational symmetry enhances the interaction between the layers. Overall, this Thesis advances the understanding of electronic energy transfer and nonequilibrium dynamics in moving systems beyond the limits of linear response theory.