We used FHI-aims instead of CP2K for the force evaluation since the TS dispersion correction, added as postprocessing step to the electronic forces, is not implemented in CP2K. A proper choice of the dispersion correction model is crucial to keep the AIMD trajectories stable, as discussed in detail in Section 5.1. However, the dispersion correction is irrelevant for the electronic-structure optimization and does consequently not affect the computation of the dipole moments and polarizabilities for the single snapshots. Figure (SI) demonstrates that the CP2K and FHIaims calculations generate very similar electronic potential energy surface (PES). This ensures that the frequencies (via forces/velocities from FHI-aims) and the corresponding IR/Raman intensities (from CP2K) are treated on equal footing.