Regensburg 2022 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 46: Poster Session: Complex Fluids, Soft Matter, Active Matter, Glasses and Granular Materials

DY 46.17: Poster

Thursday, September 8, 2022, 15:00–18:00, P2

Fisher-Widom line for systems with competing repulsive and attractive interaction — •Matthias Gimperlein and Michael Schmiedeberg — FAU Erlangen-Nuremberg, Germany

We study colloid-polymer mixtures interacting via a Double-Square-Well potential (DSW-potential) consisting of hard core repulsion, short range attraction and longer range repulsive interaction. The Fisher-Widom line (FW-line) can be used as an indicator for the interplay between repulsion and attraction in the system. It seperates regimes of monotonically (attraction dominates) or oscillatory (repulsion dominates) decaying pair correlation function in the phase diagram.
Solving the Ornstein-Zernike equation we find that the regime of monotonically decaying pair correlation function decreases. On the high density side of the phase diagram repulsion dominates (hard core interaction), but the introduction of the longer range repulsive step leads to a dominance of repulsion also on the low density side of the phase diagram. Only for intermediate densities and temperatures close to the critical temperature attraction dominates the system.
Further research includes a detailed check and analysis of the theoretical results by Brownian Dynamics simualtions. The intersection of the binodal and the FW-line could be interesting for the structure of systems below the binodal line and eventually for gel network formation.