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