Anomalous Vapor and Ice Nucleation in Water at Negative Pressures: A Classical Density Functional Theory Study

TL;DR

This study uses classical density functional theory to explore the complex, non-monotonic behavior of vapor and ice nucleation in metastable water at negative pressures, revealing novel insights into water's thermodynamic anomalies.

Contribution

It provides a unified theoretical framework for understanding vapor and ice nucleation in metastable water, especially at negative pressures, highlighting non-monotonic temperature dependencies and reentrant behaviors.

Findings

Non-monotonic temperature dependence of liquid-vapor surface tension.

Decoupling of minimum vapor nucleation barrier temperature from maximum density.

Reentrant ice nucleation barrier behavior along isotherms.

Abstract

In contrast to the abundance of work on the anomalous behavior of water, the relationship between the water's thermodynamic anomalies and kinetics of phase transition from metastable water is relatively unexplored. In this work, we have employed classical density functional theory to provide a unified and coherent picture of nucleation (both vapor and ice) from metastable water, especially at negative pressure conditions. Our results suggest a peculiar non-monotonic temperature dependence of liquid-vapor surface tension at temperatures where liquid-vapor coexistence is metastable with respect to the ice phase. The vapor nucleation barrier on isochoric cooling also shows a non-monotonic temperature dependence. We further note that, for lower density isochores, the temperature of minimum vapor nucleation barrier ($T_{\Delta \Omega_{\rm v/min}^*}$) does not coincide with the temperature of maximum density (TMD) where metastability is maximum. The temperature difference between the $T_{\Delta \Omega_{\rm v/min}^*}$ and the TMD, however, decreases with increasing the density of the isochore, suggesting a strong correlation between the propensity of cavitation and metastability of the liquid water at high densities. The vapor nucleation barrier along isobaric cooling shows an interesting crossover behavior where it first increases on lowering the temperature and then shows a non-monotonic behavior in the vicinity of the Widom line on further lowering the temperature. Our results on the ice nucleation from metastable water show an anomalous retracing behavior of the ice nucleation barrier along isotherms and theoretically validate the recent findings that the reentrant ice(Ih)-liquid coexistence can induce a drastic change in the kinetics of ice nucleation. In addition, this study also provides deeper insights into the origin of the isothermal compressibility maximum on isochoric cooling.