Regensburg 2019 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Wetting, Fluidics and Liquids at Interfaces and Surfaces (joint session CPP/DY)

CPP 20.4: Talk

Tuesday, April 2, 2019, 10:15–10:30, H13

A Direct Inversion Approach to Local Permittivity at Liquid-Liquid Interfaces — •David Egger, Christoph Scheurer, and Karsten Reuter — Theoretische Chemie, TU München

Realistic models for catalytic reactions at liquid-liquid interfaces (LLIs) require a profound knowledge of the electrostatic properties in the vicinity of the solvated catalytic complex. For polar fluids like water, these properties as described by the static dielectric constant, ε, can be related to thermal equilibrium fluctuations of the polarization at zero field.

The Kirkwood-Fröhlich (KF) approach usually applied in the derivation of such formulas faces two major difficulties: First, correlated polarization fluctuations are long-range and subject to slow convergence, making KF expensive in simulations. Second, the difficulty of the electrostatic boundary value problem one needs to solve in a KF ansatz increases with the systems’ complexity. In this contribution, we present a possible alternative procedure, following the reciprocal space formalism described by Neumann for wave-vectors at finite wavelength [1].

Exploiting the convolutional relation between dipole-dipole interaction tensor and polarization, we present a cavity kernel based approach in reciprocal space in order to arrive at local real space averages to calculate a spatially resolved ε(r) from spheroidal gaussian cavities of different shape and volume, avoiding difficulties with geometry-induced boundary conditions in the electrostatic description. Results are discussed for water bulk and water-dichloroethane LLI systems.
M. Neumann, Mol. Phys. 57:1, 97-121, 1986