Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 41: Active Matter I (Joint Session DY/BP/CPP)

BP 41.13: Talk

Wednesday, March 22, 2017, 18:15–18:30, HÜL 186

Effective interactions of active particles: interfacial phase behavior and swim pressure — •René Wittmann, Abhinav Sharma, and Joseph Brader — Departement für Physik, Universität Fribourg, 1700 Fribourg, Schweiz

We employ classical density functional theory to study the self-organization in active systems. Using a first-principles approach, we map the self-propulsion onto an effective pair interaction potential, which has been shown [1] to account for the motility-induced phase separation (MIPS) observed for active Brownian particles. We further introduce an effective external potential and investigate inhomogeneous situations.

Solely as a result of their activity, we predict [2] that active (Brownian) particles undergo a variety of interfacial phase transitions, e.g., wetting and capillary condensation in purely repulsive systems or drying and capillary evaporation of attractive colloids. We explain why the effective thermodynamic pressure and interfacial tension do not coincide with the mechanical results, which we recover by embedding the presented effective-potential approach within a more general (dynamical) framework. Finally, we comment on situations with a non-vanishing particle current [3].
[1] T. F. F. Farage, P. Krinninger and J. M. Brader, Phys. Rev. E 91, 042310 (2015).

[2] R. Wittmann and J. M. Brader, Europhys. Lett. 114, 68004 (2016).

[3] A. Sharma, R. Wittmann, J. M. Brader, arXiv:1611.03897 (2016).