Dresden 2026 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Complex Fluids and Soft Matter (joint session DY/CPP)

CPP 20.12: Talk

Tuesday, March 10, 2026, 12:30–12:45, ZEU/0160

Electric double layers - the software package capDFT — Fabienne Dressler and •Andreas Härtel — Institute of Physics, University of Freiburg

Electric Double Layers are used to store electric energy, they can be utilized to harvest energy from waste heat or steps in concentrations, and they stabilize colloidal systems. In all cases, mobile ions arrange themselves to screen surface charges, resulting in sometimes densely packed regions of microscopic particles far from bulk states that dominate the macroscopic physical properties of the system. Modeling these complex systems has theoretical and numerical limitations, but good although expensive solutions exist. We present an open-source software package to treat the described modeling utilizing classical density functional theory [1]. The package has been used successfully in studies of underscreening [2] and allows to go beyond the standard mean-field approximation of primitive models [3]. We will demonstrate the package by discussing an example, where we study capacities of structured electrodes.

[1] https://github.com/andreashaertel/capdft

[2] Anomalous Underscreening in the Restricted Primitive Model. A. Härtel, M. Bültmann, and F. Coupette. Phys. Rev. Lett. 130, 108202 (2023)

[3] The primitive model in classical density functional theory: beyond the standard mean-field approximation. M. Bültmann and A. Härtel. J. Phys. Condens. Matter 34, 235101 (2022)

Keywords: DFT; EDL; screening; electrolytes; supercapacitors