Electric Field Effects on Dielectric and Thermal Properties of Water: Role of Water Models in Electrothermal Response of Molecular Simulations

The interaction of water molecules in response to external electric fields plays a crucial role in a wide range of scientific and engineering applications, such as energy conversion, electrochemical systems, environmental remediation, and biomedical processes. Designing and refining these technologies requires an understanding of the molecular scale coupled electro-thermal response of water. In this study, molecular dynamics (MD) simulations on water have been performed to resolve the dielectric and thermal behavior under varying electric fields. Five of the classical MD water models, such as SPC/E, TIP4P, TIP4P/2005, TIP4P/ε, and TIP4P/XAIe, were used to evaluate their performance under varying electric field strengths. The dielectric constant exhibits a nonlinear decline with increasing field, reflecting dipolar saturation; TIP4P/XAIe and TIP4P/ε provide the most accurate responses, while TIP4P shows the largest deviations. Thermal conductivity decreases slightly with field due to restricted molecular rotations, with SPC/E and TIP4P/2005 producing values closest to experiment, though all models overestimate because of their nonpolarizable nature. Self-diffusion remains constant below 0.1 V/Å and declines linearly in higher fields, indicating a reduced molecular mobility. Moreover, unlike older models like TIP4P and SPC/E, recently developed water models (TIP4P/XAIe and TIP4P/ε) exhibit field-induced structural ordering toward ice-like phases and successfully capture electro-freezing transitions, while TIP4P/2005 shows partial electro-freezing behavior. These discoveries offer important insights into the microscopic processes that control the electro-thermal response of water and provide helpful recommendations for the selection and creation of precise water models for modeling electrochemical, energy, and environmental applications.