Molecular dynamics simulations of liquid–liquid interfaces in an electric field: The water–1,2-dichloroethane interface

Abstract

The polarized interface between two immiscible liquids plays a central role in many technological processes. In particular, for electroanalytical and ion extraction applications, an external electric field is typically used to selectively induce the transfer of ionic species across the interfaces. Given that it is experimentally challenging to obtain an atomistic insight into the ion transfer process and the structure of liquid-liquid interfaces, atomistic simulations have often been used to fill this knowledge gap. However, due to the long-range nature of the electrostatic interactions and the use of 3D periodic boundary conditions, the use of external electric fields in molecular dynamics simulations requires special care. Here, we show how the simulation setup affects the dielectric response of the materials and demonstrate how by a careful design of the system it is possible to obtain the correct electric field on both sides of a liquid-liquid interface when using standard 3D Ewald summation methods. In order to prove the robustness of our approach, we ran extensive molecular dynamics simulations with a rigid-ion and polarizable force field of the water/1,2-dichloroethane interface in the presence of weak external electric fields.

Potential dependence of the ionic structure at the ionic liquid/water interface studied using MD simulation

“…66 Raiteri et al gave the positive and negative charges to the two solid electrodes which sandwich the O-W two-phase system, although they did not add ions into the system and therefore no EDL was formed at the interface. 67 We adopted the latter strategy by sandwiching the IL-W two-phase system with two graphene plates (Fig. 1b, see SI for the preparation), which we confirmed to be effective in our previous MD studies on the EDL structure in ILs.…”

Potential Dependence of the Ionic Structure at the Ionic Liquid/water Interface Studied Using MD Simulation

“…65 Raiteri et al gave the positive and negative charges to the two solid electrodes which sandwich the O-W two-phase system, although they did not add ions into the system and therefore no EDL was formed at the interface. 66 We adopted the latter strategy by sandwiching the IL-W two-phase system with two graphene plates (Fig. 1b, see SI for the preparation), which we confirmed to be effective in our previous MD studies on the EDL structure in ILs.…”

Electromagnetic bioeffects: a multiscale molecular simulation perspective

“…A recent study demonstrated the importance of careful simulation design and setup to accurately model the dielectric response of the materials and that it is possible to obtain the correct EF on both sides of a liquid–liquid interface when using standard 3D Ewald summation methods. 116…”