Electronic correlation effects in the stopping power of ions in 2D materials

The energy loss of charged projectiles in correlated materials is of prime relevance for plasma-surface interaction for which we have developed a nonequilibrium Green functions (NEGF) approach. A particularly interesting effect is the \textit{correlation induced increase} of stopping power at low velocities\footnote{Balzer \textit{et al.}, \textit{Phys. Rev. Lett.} {\bf 121}, 267602 (2018)}. However, NEGF simulations are possible only for short time durations, due to the unfavorable $N_t^3$ scaling with the number of discretization time steps. The situation has changed radically with the recently developed G1-G2 scheme\footnote{Schluenzen \textit{et al.}, \textit{Phys. Rev. Lett.} {\bf 124}, 076601 (2020)}, which is based on the generalized Kadanaoff-Baym ansatz in combination with Hartree-Fock propagators, and allows to \textit{achieve linear scaling} with $N_t$. This enhancement enables us to improve previous simulations by using better selfenergies\footnote{Joost \textit{et al.}, Phys. Rev. B \textbf{101}, 245101 (2020)}, studying larger systems and by extending the simulation duration which gives access to slower projectiles. Finally, we will report further improvements of the G1-G2 scheme itself, by taking into account three-particle correlations.