Using Polarizable Force-Field Based Molecular Dynamics Simulations to Understand Electronic Polarization Effects in Interfacial Phenomena*

Hexagonal boron nitride (hBN) is a wide-bandgap insulator known for its remarkable properties such as high thermal conductivity, extensive bandgap, significant chemical stability, and sturdy mechanics. In recent years, it has gained notable attention because of its potential uses in areas like seawater purification, nanofluidic energy collection, biological sensing, and separating oil from water. In many of these applications, the hBN surface frequently interacts with polar molecules, such as water, and charged species like salt ions, which can generate strong electric fields, leading to a pronounced electronic polarization on the hBN surface. Due to the vectorial nature of the electric fields, the polarization energy is inherently non-additive and exhibits a many-body character. Therefore, gaining a foundational understanding of the role of electronic polarization effects on the thermodynamic and transport properties of water molecules and salt ions at hBN/water interfaces is important. However, previous Molecular Dynamis (MD) simulation studies have neglected the polarization effects of hBN when interacting with water molecules and salt ions. In this study, we formulate a theoretical framework that introduces all-atomistic polarizable force fields to accurately model the anisotropic polarizability tensor of hBN and its interactions with water and ions. By carrying out MD simulations using the new polarizable force fields, we investigate the role of many-body polarization interactions on the contact angle of water on hBN layers and the thermodynamics of salt ions at hBN/water interfaces. Overall, our study underscores the important role played by polarization effects in dictating the water orientation, the wetting behavior, and the solvation process of ions at the hBN/water interface.