Cooperativity and hydrogen bond network lifetime in liquid water.

Abstract

The lifetime of the H bond network has been calculated as a function of temperature by a statistical five-species model for water in which the H bond cooperativity has been explicitly taken into account. While, on one hand, the Arrhenius behavior of the depolarized Rayleigh scattering data existing in an intermediate temperature region is well reproduced, the model predicts that the H bond lifetime diverges as the supercooled temperature limit is approached. The observed cooperative stabilization of the H bonds in tetracoordinated molecules occurring in the deep supercooled region, where this species becomes the most long-lived one, points out the tendency of the system to unavoidably approach ice rather than to reach a region of dynamical instability.