UBI seminar (50th) 2020年1月9日 14:00~
 Venue:駒場第一キャンパス10号館403室
 Speaker:Dr. Simon Schnyder(京大・福井センターフェロー)              
 Title:Crowding in Heterogeneous Media: Breakdown of Universality for            Soft Interactions

Abstract: In heterogeneous materials, such as in biological cells, porous media or ionic conductors, anomalous diffusion is observed, i. e. the mean-squared displacement (MSD) of a tracer particle grows sub-diffusively over long periods of time. A paradigm for modeling of transport in heterogeneous media is the Lorentz Model, in which a single mobile particle moves in a static matrix built of overlapping hard disk obstacles. There, anomalous diffusion is the signature of a universal localization transition caused by the percolation of the matrix. In experiments and simulations, a wide range of exponents have been reported, and it remains unclear if those exponents represent transient behavior, or whether they can be connected to a universal behavior. We generalized the Lorentz Model in molecular dynamics simulations by introducing interacting tracer particles and soft interactions and performed experiments of a colloidal Lorentz Model. We showed that due to the soft interactions the localization transition becomes rounded and that the universality of the dynamics breaks down.

References:
1) T.O.E. Skinner et al, PRL 111, 128301 (2013).
2) S.K. Schnyder et al, Soft Matter 11, 701 (2015).
3) S.K. Schnyder et al, PRE 95, 032602 (2017).
4) S.K. Schnyder & J. Horbach, PRL 120, 78001 (2018).