In contrast, photodynamics simulations for C 4 H 8 employing PaiNN-based SpaiNN models outperform those using SchNet-based counterparts. However, both models exhibit reliability limitations, constrained to a simulation time of approximately 60 fs, as indicated by the gray region in Figure5 and S14, determined by the total energy of the molecules at each time-step of the dynamics simulation. This is due to the fact that the C 4 H 8 database was not optimized through active or online learning, hence the simulations fail for both SchNet-and PaiNN-based SpaiNN models after reaching a certain simulation time, corresponding to long-tail events not well represented in the training data. Only the PaiNNbased SpaiNN model accurately reproduces the population kinetics of butene with respect to the reference, yielding a lifetime of the initially excited S 1 state of 49 fs, consistent with reference calculations (48 fs), while SchNet-based models yield a lifetime of about 15 fs (Figure ). This underscores the influence of the more accurate excited-state properties of PaiNN compared to SchNet-based SpaiNN models.