Abstract

Ions shooting through matter transfer energy to the electrons along its trajectory at rates of up to keV per Angstrom. This rate depends on the projectile velocity, peaking when it is similar to average electron velocities in the system, typically around two to five percent of the speed of light. Because of its interest to radiation damage in various contexts (mostly nuclear, aerospace, and medical), the problem has been studied for over a century, but surprisingly little is known about the microscopic processes taking place beyond what obtained from perturbative approaches. The problem is strongly non-adiabatic and very strongly far from equilibrium. It is also nanoscopic (around the projectile) and of quantum nature. I will present our efforts in advancing our understanding of such processes by means of simulations based on time-dependent density-functional theory in real time, with special emphasis on the dependence on the chemistry of the irradiated matter, but also some notes on methodological advances prompted by the problem, in particular on quantum evolution in an evolving Hilbert space.