(applied to the first 20 fs of the simulations) we obtain the exciton localization time constants τ loc presented in the right column of Tab. 2. These time constants amount to ∼6-7 fs, which means extremely ultrafast further localization (of initially quite strongly localized nπ * excitons) originating from the short-time excited-state dynamics. The fits obtained using eq. ( ) are also shown in the right panel of Fig. . We should note that the fits do not reproduce the details of the PN curves obtained from the numerical simulations, but they allow as to obtain a characteristic time of the extremely ultrafast localization process occurring during excited-state dynamics. of the studied systems is shown in Fig. , for the first 20 fs of dynamics. For the shown trajectories, the initial electronic state is either S 3 or S 4 (see the last row of Fig. ). However, the internal conversion to the S 1 state takes only ∼5 fs. The initial exciton is strongly localized on a single fragment -X = 1 for all systems except tetramer 3.5, for which X = 3 in the given case. The initial localization is transiently perturbed during internal conversion, but subsequently recovered, and the exciton stays localized while the aggregate evolves in the S 1 state. We note that no exciton transfer occurs during the short-time dynamics, i.e., the same fragment X bears exciton at t = 0 and t = 20 fs (for the same trajectory). [For few trajectories the short-time exciton transfer is observed as exemplified in Fig. .] The transient localization perturbation / delocalization is logically reflected in the PN curves, which deviate from 1 at corresponding times (see the third row of Fig. ). This behavior correlates with the non-monotonic, short-time evolution of the ensemble-averaged PN curves shown in Fig. , right. At that, the excitons are composed of local excitations, and CT ≈ 0 Next, considering the entire simulation period of 10 ps, we find virtually no exciton transfer (at longer times) while the systems evolve in the nπ * manifold. There are only three trajectories demonstrating the opposite (see Fig. ). The very rare occurrence of the nπ * exciton transfer is in agreement with our previous simulations of the ππ * dynamics (where the nπ * states are reached via internal conversion from the ππ * states). Moreover, it agrees with the previous simulations of Sangiogo Gil, Persico, and Granucci based on an exciton model. However, for some trajectories the exciton transfer occurs via nπ * → ππ * → nπ * or nπ * → S 0 → nπ * pathways (see Fig. ). These pathways involve upward hops that require a certain amount of kinetic energy to occur, since the change in the potential energy caused by the hop should be compensated to conserve the total energy. In this respect we note that there is no energy dissipation to environment in our models; therefore, the upward hops are facilitated in the present simulations.