Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Interfaces and Thin Films I

CPP 14.1: Vortrag

Montag, 12. März 2018, 15:00–15:15, C 264

Permittivity at Liquid-Liquid Interfaces: An Iterative Reaction Field Approach — •David Egger, Karsten Reuter, and Christoph Scheurer — TU München

Realistic models for catalytic reactions at liquid-liquid interfaces 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 reaction field approach described by Neumann for cubic and spherical sample shapes [1]. Exploiting the constant reaction field of oblate spheroidal dielectric bodies immersed in continuum dielectrics, we present an iterative method to calculate a spatially resolved ε from cavities of different shape and volume, avoiding difficulties with geometry-induced boundary conditions in the electrostatic description. Gaussian error regression is further applied to drive down statistical errors, exploiting the presupposed continuitiy of the dielectric tensor field. Results are discussed for water bulk and water-dichloroethane interfacial systems.

[1] M. Neumann, Mol. Phys. 50, 841 (1983).