Influences of core-electron excitation and charge-polarization effect on the electronic stopping of Fe for Fe projectiles

The electronic stopping power of Fe ions traveling through Fe is investigated using nonequilibrium simulations of the electronic response via real-time time-dependent density functional theory. The role of core electrons of both projectiles and host atoms on the electronic stopping power are investigated by explicitly incorporating core electrons in simulations. This study finds that the effect of the projectile's core electrons on electronic stopping power surpasses that of the core electrons of the target atoms. The steady-state charges of projectiles with varying electron configurations are calculated to assess the Bethe formula's applicability. Furthermore, the electronic stopping power of the projectiles traversing through Fe along the channeling trajectory is studied. The results show that the charges captured by channeling projectiles exhibit a polarization effect in the medium- and high-velocity regimes, leading to a high electronic stopping power.