Doublon Production in Correlated Materials by Multiple Ion Impacts

In a recent Letter [Balzer \textit{et al.}, Phys. Rev. Lett. \textbf{121}, 267602 (2018)] it was demonstrated that ions impacting correlated graphene cluster can excite strongly nonequilibrium states. particular, this lead to an enhanced population of bound pairs electrons with opposite spin -- doublons where the doublon number be increased via multiple ion impacts. These predictions were made based on Green functions (NEGF) simulations allowing for time-dependent non-perturbative study energy loss charged particles penetrating system. Here we extend these larger clusters and longer simulation times, utilizing recently developed G1--G2 scheme [Sch\"unzen \textbf{124}, 076601 (2020)] which allows dramatic speedup NEGF simulations. Furthermore, investigate dependence time interval between impacts impact point.