Screening in Liquid Water

Abstract

We argue that screening is responsible for the presence of an unattainable critical temperature T c ≃ −46C in liquid water at which characteristic times have a power-law divergence.1 It is generally agreed that to understand the origin of T c , one must look into the organization of the complicated network of hydrogen bonds in liquid water. Here, one apparent ‘paradox’ is that although the hydrogen binding energy is an order of magnitude larger than kT at temperatures about 0°C, the network of hydrogen bonds are reorganizing within a time scale of picoseconds. It is however in this problem the mechanism for the anomalous behavior of liquid water is found. Recent studies2 suggest that the reorganization of the hydrogen-bond network is mediated by the presence of ‘excess’ molecules in the first coordination shell. In this case ‘bifurcated’ bonds may form—instead of one ‘good’ hydrogen bond with binding energy E, two or more bonds are formed sharing this energy.