Evaluation of the grand-canonical partition function using Expanded Wang-Landau simulations. V. Impact of an electric field on the thermodynamic properties and ideality contours of water

TL;DR

This study uses expanded Wang-Landau simulations to evaluate how electric fields influence water's thermodynamic properties, revealing significant shifts in phase behavior, critical temperatures, and structural order across various conditions.

Contribution

It provides a detailed analysis of electric field effects on water's thermodynamics using grand-canonical simulations, highlighting shifts in phase properties and structural order.

Findings

Electric fields cause up to 20% shifts in chemical potential at vapor-liquid coexistence.

Critical temperatures increase by nearly 7% under a 0.2 V/Å field.

Vaporization entropies increase by up to 35%.

Abstract

Using molecular simulation, we assess the impact of an electric field on the properties of water, modeled with the SPC/E potential, over a wide range of states and conditions. Electric fields of the order of $0.1V/$\AA and beyond are found to have a significant impact on the grand-canonical partition function of water, resulting in shifts in the chemical potential at the vapor-liquid coexistence of up to $20$%. This, in turn, leads to increases in the critical temperatures by close to $7$% for a field of $0.2V/$\AA, to lower vapor pressures, and to much larger entropies of vaporization (by up to $35$%). We interpret these results in terms of the greater density change at the transition and of the increased structural order resulting from the applied field. The thermodynamics of compressed liquids and of supercritical water are also analyzed over a wide range of pressures, leading to the determination of the Zeno line and of the curve of ideal enthalpy that span the supercritical region of the phase diagram. Rescaling the phase diagrams obtained for the different field strength by their respective critical properties allows us to draw a correspondence between these systems for fields of up to $0.2V/$\AA.