Water Thermodynamic Behavior Under Influence of Electric Field: A Molecular Dynamics Study

Abstract

Water phase-change is of importance to many applications including energy conversion, thermal management of electronics, and medical therapies. Augmenting the rate of phase-change by application of an electric field is of interest in many situations and may lead to increased effectiveness of energy transfer. Thus, it is important to develop a better understanding of the effect of an electric field on the thermodynamic properties of water. In this work, molecular dynamics (MD) was utilized to assess two distinct water models, the TIP4P-Ew and the SWM4-NDP, for predicting the effect of an electric field on the density and the enthalpy of vaporization of water. Both water models possess rigid molecular geometry. However, the SWM4-NDP model has a negatively charged Drude particle (the “NDP”) attached to the oxygen site in the water molecule, making the SWM4-NDP model polarizable. The objective is to understand if the polarizability of the water model has a significant effect when predicting the two properties of interest. Applying an electric field in MD simulations with each water model resulted in increased values for both the density and enthalpy of vaporization. The magnitude of these increases is comparable between water models and grows with applied field strength. Corresponding electrostriction pressure attributed to the applied field is well below values predicted by analytical models.