Abstract

Time-dependent density functional theory coupled with molecular dynamics is used to study electronic excitations produced by energetic protons in solid copper over a wide range of proton velocities. A plane-wave pseudopotential scheme is employed to solve the time-dependent Kohn-Sham equations for a moving ion in a periodic crystal. These electronic excitations determine the stopping power of the material and alter the interatomic forces for both channeling and off-channeling trajectories. Our off-channeling results are in quantitative agreement with experiments. Present results unveil a region of superlinear velocity dependence related to copper crystalline band structure.