Furthermore, we performed conventional DFT-based AIMD simulations as a comparison. The results are presented in Figure . AIMD gives a peak value of 3382 cm -1 for the Type IIa hydrogen bonded O-H stretch, which is more than 300 cm -1 higher than the CNEO-MD result and is significantly separated from the C-H stretch region. This large difference between the CNEO-MD and AIMD results demonstrates again the crucial role of quantum nuclear delocalization during MD simulations of hydrogen bonding systems.