Hydrogen-bond dynamics for the extended simple point-charge model of water

We study hydrogen-bond dynamics in liquid water at low temperatures using m olecular dynamics simulations. We analyze the dynamics using energetic and geometric definitions of a hydrogen bond, and employ two analysis methods: (i) a history-dependent correlation function, related to the distribution o f bond lifetimes, and (ii) a history-independent correlation function. For method (i) we find an approximately Arrhenius temperature dependence of the bond lifetime, and find that the distribution of bond lifetimes is extreme ly sensitive to the choice of bond definition. For method (ii) we find-inde pendent of bond definition-that the dynamics are consistent with the predic tions of the mode-coupling theory, suggesting that the slow dynamics of hyd rogen bonds can be explained in the same framework as standard transport qu antities. Our results allow us to clarify the significance of the choice of both bond definition and analysis technique.