In the present paper, we perform nonadiabatic, surface hopping molecular dynamics simulations for QM tetramer models (with and without additional steric constraint of surrounding MM molecules; and for short and longer intermolecular separation distances) to reveal the fate of the excitons after photoexcitation. We explore the exciton dynamics using a transition density matrix analysis, allowing one to judge on spatial localization of excitons during dynamics. In the present study, we treat the electronic subsystem of the tetramers fully quantum mechanically (albeit on a semiempirical level described in the next section), without resorting to more approximate descriptions, such as exciton models.