Regensburg 2022 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 49: Statistical Physics: General

DY 49.4: Talk

Friday, September 9, 2022, 10:15–10:30, H20

Classical density functional theory and the primitive model: beyond the standard mean-field approximation — •Moritz Bültmann and Andreas Härtel — Albert-Ludwigs-Universität Freiburg, Physikalisches Institut

To understand the physics of electrolyte solutions one often uses the primitive model, where ions are represented by charged hard spheres in a dielectric background. The powerful theory of density functionals, which is widely known from quantum mechanics, can also be applied to such systems in the context of statistical physics. There, the first order of a functional perturbation yields the mean-field electrostatic functional, which also contributes at particle separations that are forbidden due to the hard-core interations.

In this talk I summarize our findings from the article [J. Phys.: Condens. Matter 34 235101], where we modified the mean-field functional such that the occuring pair potential is constant for distances smaller than hard-core contact. The resulting formalism involves weighted densities similar to the ones used in most hard-sphere functionals. Comparing different functionals and result from MD simulations, we analyze density profiles, direct and total correlation functions, and thermodynamic sum rules. Thereby, we found that the modifications improved the predictions compared to the standard mean-field functional significantly. Finally, I report on recent findings of the modified mean-field functional e.g. concerning the decay behavior of total correlation functions.