Cooperative hydrogen bonding and structural instability in water

Abstract

We propose a model for liquid water in which the bonding states of each molecule are represented by a 5-level equivalent system. The structural effects are taken into account in a theoretical approach of the « mean-field » type, the mean-field (internal pressure) being supposed to decrease when the number of 4-bonded molecules increases. The model predicts the dependence of several thermodynamical parameters on T and P, and the existence of a structural stability limit which implies a divergence of α P, βT and Cp in the supercooled state. The existence of a structural critical point is discussed