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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.32: Poster

Tuesday, March 19, 2024, 18:00–20:00, Poster E

Understanding electrolyte transport properties with interfaces under applied forces: Insight from MD-simulations — •Katharina Kintrup¹, Youssef Mabrouk^{1, 2}, Diddo Diddens^{1, 2}, and Andreas Heuer¹ — ¹Institut für Physikalische Chemie, Corrensstraße 28/30, 48149 Münster, Deutschland — ²Helmholtz-Institut Münster, Corrensstraße 48, 48149 Münster, Deutschland

Transport properties of electrolytes can be conveniently studied via Molecular dynamics (MD) simulations. However, whereas typically MD simulations are performed with periodic boundary conditions (pbc), experimental systems involve fixed electrodes. As a consequence, the conservation of momentum, observed in MD simulations, is violated. Indeed, previous electrophoretic NMR (eNMR) experiments suggest that the conservation of local volume [1] rather than momentum conservation is the mobility determining constraint.

We performed molecular dynamics (MD) simulations for a simplified binary model, imitating ionic liquids. Starting with an equilibrium configuration, we record the respective center-of-mass velocities after application of an electric field for both boundary conditions and for various box sizes. Whereas in the presence of pbc momentum is naturally conserved, we observe a complex oscillatory time dependence of the two velocities with fixed walls. Their ratio approaches a value nearly compatible with local volume conservation, in qualitative agreement with experiment. A physical picture is formulated, based on the emergence of the generation of standing sound waves. [1] J. Phys. Chem. Lett. 2022, 13, 37, 8761-8767

Keywords: MD simulations; transport of electrolytes; impact of boundary conditions; sound waves