Berlin 2024 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 29: Statistical Physics of Biological Systems II (joint session BP/DY)

BP 29.2: Vortrag

Donnerstag, 21. März 2024, 09:45–10:00, H 1028

Designing phase coexistence in multicomponent mixtures: surface tensions and the Gibbs’ rule — •Filipe Thewes and Peter Sollich — Institut für Theoretische Physik, Georg-August-Universität Göttingen, Göttingen, Germany

Gibbs’ phase rule constrains the maximum number of phases that can coexist in multicomponent mixtures. It relates the maximum number of phases to the number of components and the degrees of freedom. The phases formed in equilibrium depend directly on the interactions between the different components, opening the possibility for the inverse problem of designing a set of interactions that recover a desired phase behavior. This perspective has been explored recently in relation to phase separation in biological systems as a mechanism for cells to control their internal structure and function. Interestingly, recent approaches for such interactions design are able to retrieve in the grandcanonical setting a number of phases that is larger than predicted by a naive application of Gibbs’ phase rule. In this talk, I will first revisit Gibbs’ rule in the grandcanonical ensemble and show that designed interactions act as new degrees of freedom that do increase the number of possible phases. I then show that in a canonical setting the number of phases is determined by interfacial tensions; above the naive Gibbs limit we find long-lived metastable states in numerical simulations. In the second part, I will discuss which conditions on the interfacial tensions result in “super-Gibbs” canonical phase splits. These conditions lead to a second step in the design problem of multicomponent mixtures, namely that of controlling the interfacial properties.