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

Abstract Water phase-change is one of the most widely used mechanisms to transfer heat, with applications in both cooling and energy conversion. Augmenting phase-change effectiveness by application of an electric field is of interest in many situations and may lead to increased system efficiency with sustainability implications. 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, but 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. It is desired to observe how important this polarizability is to predicting density and enthalpy of vaporization. Applying an electric field in MD simulations with each water model results in increased values for both the density and enthalpy of vaporization. The magnitude of these increases are comparable between water models and increase with increasing field strength.