Electric fields at solid-liquid interfaces: Insights from molecular dynamics simulation

In this manuscript, we explore the electrostatic environment of the interface between a solid and a dilute electrolyte solution, with an emphasis on the electric field profiles that these systems produce. We review the theoretical formalism that connects electrostatic potential profiles, electric field profiles, and charge density fields. This formalism has served as the basis for our understanding of interfacial electric fields and their influences on microscopic chemical and physical processes. Comparing various traditional models of interfacial electrostatics to the results of molecular dynamics (MD) simulation yields mutually inconsistent descriptions of the interfacial electric field profile. We present MD simulation results demonstrating that the average electric field profiles experienced by particles at the interface differ from the properties of traditional models and from the fields derived from the mean charge density of atomistic simulations. Furthermore, these experienced electric field profiles are species-dependent. Based on these results, we assert that a single unifying electrostatic potential profile - the gradient of which defines a single unifying electric field profile - cannot correctly predict the electrostatic forces that act on species at the interface.