Using Activation Energies to Elucidate Mechanisms of Water Dynamics

Recent advances in the calculation of activation energies are shedding new light on the dynamical time scales of liquid water. In this Perspective, we examine how activation energies elucidate the central, but not singular, role of the exchange of hydrogen-bond (H-bond) partners that rearrange the H-bond network of water. The contributions of other motions to dynamical time scales and their associated activation energies are discussed along with one case, vibrational spectral diffusion, where H-bond exchanges are not mechanistically significant. Nascent progress on outstanding challenges, including descriptions of non-Arrhenius effects and activation volumes, are detailed along with some directions for future investigations.

Automated summary

Recent advancements in the calculation of activation energies have provided new insights into the dynamical time scales of liquid water. This Perspective examines the central role of hydrogen-bond exchanges in the rearrangement of water's hydrogen-bond network, while also discussing the contributions of other motions to dynamical time scales and activation energies. Progress on outstanding challenges such as non-Arrhenius effects and activation volumes is detailed, along with directions for future investigations.