To obtain additional mechanistic insights into the relaxation process in the NAMD simulations, in Figure the final O-H distance values were plotted against the corresponding final trajectory time (i.e., either the final time of 300 fs set for the dynamics, or the time at which the applied stopping condition was satisfied). While the collapsed group of points at t = 300 fs corresponds to the unreactive trajectories, all other points, positioned at t < 300 fs, mark events of successful excited state relaxation to S 0 . It can be seen that all the reactive points, except two at t ≈ 250 fs, show strong elongation of the original O-H bond, indicating the PT from MeOH to PrdPyr as the deactivation mechanism. The mean value of the O-H distance at the moment of the S 1 → S 0 hopping is similar in all systems, increasing slightly from PPMet-4 (1.40 ± 0.01 Å), through PPMet-6 (1.47 ± 0.01 Å), to PPMet-1 (1.53 ± 0.01 Å) which is in overall agreement with the predictions formulated on the grounds on the PEPs analysis. Moreover, if one has a look at the correlation between initial velocities of atoms involved in the HB formation (Figs. S11-S13 in the ESI), and the individual trajectories outcome, it can be observed that large kinetic energy initially accumulated in the HB-proton vibrations effectively supports the EDPT process.