Electronic stopping in warm dense matter using Ehrenfest dynamics and time-dependent density functional theory*

Ehrenfest dynamics with time-dependent density functional theory (TDDFT) provides a framework for first-principles calculations of electronic stopping power that has been successfully applied in the solid state in numerous contexts. Its use in the warm dense regime has not been as widely studied, in part due to the computational expense of treating a large number of thermally occupied orbitals. In this talk, we examine some of the challenges associated with scaling Ehrenfest+TDDFT into the warm dense regime. We first consider isochorically heated aluminum, which allows us to study the impact of the pseudization of the L-shell under conditions in which it is increasingly thermally depleted. We then consider all-electron calculations of liquid-like deuterium and carbon to study the impact of finite-size effects and configurational averaging as a function of projectile energy. We conclude by taking the lessons we have learned to the analysis of electronic stopping in deuterium/beryllium mixtures relevant to fusion experiments. Throughout, we work within the context of validating average-atom models for the elemental systems and providing benchmark data for mixtures. We also report on some of the computational aspects of these calculations, which are among the largest of their kind.