Then, the forward rate constant k for hydrogen bond breakage and the backward rate constant k′ for hydrogen bond formation were determined from the reactive flux correlation K(t) = kc(t) – k′n(t), where c(t) is the autocorrelation function of h(t) and n(t) is the probability that a hydrogen bond that existed at t = 0 is broken, but the groups forming the hydrogen bond are still within the hydrogen bonding distance. For details of the lifetime determination, see ref 63