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

Abstract

We study hydrogen-bond dynamics in liquid water at low temperatures using molecular dynamics simulations. We analyze the dynamics using energetic and geometric definitions of a hydrogen bond, and employ two analysis methods: ͑i͒ a history-dependent correlation function, related to the distribution of bond lifetimes, and ͑ii͒ a history-independent correlation function. For method ͑i͒ we find an approximately Arrhenius temperature dependence of the bond lifetime, and find that the distribution of bond lifetimes is extremely sensitive to the choice of bond definition. For method ͑ii͒ we find-independent of bond definition-that the dynamics are consistent with the predictions of the mode-coupling theory, suggesting that the slow dynamics of hydrogen bonds can be explained in the same framework as standard transport quantities. Our results allow us to clarify the significance of the choice of both bond definition and analysis technique.

q-exponential distribution in time correlation function of water hydrogen bonds

“…3), both curves can be fitted by an Arrhenius behavior (τ HB ∝ exp(−E * /RT )). This fact was observed in previous works [14] [15].…”

“…Both MD simulations and experimental data for depolarizated light scattering show an Arrhenious behavior of τ HB , where τ HB ∝ exp(−E * /RT ) and E * is an activation energy [13][14][15]. E * can be interpreted as the energy required to break a hydrogen bond (≈ 10 KJ/mol).…”

“…However, the functional behavior of P(t) has not been clearly established to date. In previous works it was found that P(t) not to verify either an exponential or a power law behavior in the liquid and supercooled region of water, regardless of the hydrogen bond definition used [14,15].…”

“…In molecular dynamics (MD), a "history-dependent" bond correlation function P(t) is used to obtain τ HB [14,15]. P(t) represents the probability that an hydrogen bond formed at a time t = 0 remained continuously unbroken and will be broken at time t.…”

Exploration of the Dynamical Evolution and the Associated Energetics of Water Nanoclusters Formed in a Hydrophobic Solvent

“…Such clusters reorganize themselves in a cooperative way on ultrafast time scales, typically on the order of picoseconds. Although such dynamics in neat polar solvents has been studied bothexperimentally 4,32 andusingmoleculardynamicsimulation, 33,34 those involving more than one solvent are sparse. Earlier studies involving binary mixtures show that the solvation time scale varies markedly with the composition of the mixture.…”