Thermodynamics of Liquid-Liquid Criticality in Supercooled Water in a Mean-Field Approximation

In a recent publication, it has been shown how a non-analytic scaling theory of critical phenomena can describe the available experimental information for the thermodynamic properties of supercooled water, when it is assumed to exhibit a liquid-liquid critical point. In this article, we present a mean-field equation of state which also represents the experimental data for supercooled water. Compared to the scaling theory, the mean-field equation has the advantage of simplicity for practical calculations of the properties of supercooled water. The insensitivity to a particular form of a critical equation of state is due to a lack of experimental data asymptotically close to the liquid-liquid critical point. Hence, while the assumed existence of a liquid-liquid critical point in water can account for the observed thermodynamic behavior of supercooled water, the actual location of such a liquid-liquid critical point cannot be determined accurately from the available experimental thermodynamic property data.