SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 44: Wetting, Fluidics and Liquids at Interfaces and Surfaces II (joint session CPP/DY)

CPP 44.11: Talk

Thursday, March 30, 2023, 12:15–12:30, MER 02

Beyond the plate capacitor: Calculating the full dielectric tensor for arbitrary system geometries — •David Egger, Christoph Scheurer, and Karsten Reuter — Fritz Haber Institute of the Max Planck Society, Berlin, Germany

Realistic models for catalytic reactions at aqueous interfaces require a profound understanding of the electrostatic properties in the vicinity of the solvated catalytic complex, in particular for (photo-)electrochemical reactions with charged intermediates. However, explicit quantum mechanical simulations of these systems on the required length- and time-scales remain oftentimes out of reach. Coarse-graining the electrostatic response of the molecular solvent into a continuum dielectric, described by the dielectric permittivity tensor ε, can hence be a necessity. Existing coarse-graining protocols for ε typically assume a separation of the dielectric response parallel and perpendicular to the active interface. This approximation is equivalent to two decoupled sets of in-series plate capacitors and ignores potential non-zero off-diagonal elements in the ε tensor.

In this contribution, we present a comprehensive and general formalism to coarse-grain molecular solvents into a truly anisotropic ε beyond this approximation. We obtain the full, spatially resolved dielectric tensor for arbitrary system geometries with no prior assumptions on boundary conditions. Common bulk and slab formulas are obtained as special cases. The approach is applied exemplarily to bulk water, water-dichloroethane liquid-liquid interfaces, and solvated platinum nanoparticles following from Wulff constructions.