Channeling electronic stopping power of lithium ions in diamond: Contribution of projectile inner-shell electrons

The electronic energy loss of Li ion in diamond under a channeling condition is studied using real-time time -dependent density functional theory. Simulations with and without inner-shell electrons explicitly considered in describing the electron configuration of projectile Li ions are performed to understand their contribution to the dissipation mechanism. It is found that the explicit involvement of inner-shell electrons is particularly important in describing the charge state of the projectile during collision, especially in the high velocity regime where the inner-shell orbital is indeed far from fully occupied during collision. Due to the overestimate of the electronic screening, Li ions with inner-shell electrons that are frozen show only a reduced and hydrogenlike capability in perturbing the host electronic system.