The obtained time scales and fitted time constants are not identical to those obtained in previous work, due to the approximations involved in the parameterization of the VC model (Section S2.1 and Figure ). In particular, while the inclusion of statespecific quadratic coupling terms has shown merit for a better description of the system (compared to preliminary simulations), Figures S6 and S7 indicate that the 3 MC states would benefit from an anharmonic description of the Fe-X bond lengths. Consequently, the 3 MLCT→ 3 MC and 3 MC→ground state dynamics are slower than in TDDFT and experiment. These deviations do not arise from the fact that the fitted time constants that are much longer than the simulation time. In fact, the very large number of trajectories affords reasonably small uncertainties, despite the fact that the time constants are much longer than the simulated time (90 respectively 100 ps versus 5 ps).