2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/109473In this review we consider those processes in condensed matter that involve the irreversible flow of energy between electrons and nuclei that follows from a system being taken out of equilibrium. We survey some of the more important experimental phenomena associated with these processes, followed by a number of theoretical techniques for studying them. The techniques considered are those that can be applied to systems containing many non-equivalent atoms. They include both perturbative approaches (Fermi's Golden Rule, and non-equilibrium Green's functions) and molecular dynamics based (the Ehrenfest approximation, surface hopping, semi-classical gaussian wavefunction methods and correlated electron-ion dynamics). These methods are described and characterised, with indications of their relative merits.LaTeX with IoP style files, 43 pages, 3 figuresMaterials ScienceMesoscale and Nanoscale Physicstext