SKM 2023 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 42: Poster: Active Matter, Soft Matter, Fluids
DY 42.2: Poster
Thursday, March 30, 2023, 13:00–16:00, P1
Dynamics and clustering of active run-and-tumble particles on two-dimensional lattices — •Lars Torbjørn Stutzer and Peter Sollich — Institut für Theoretische Physik, Georg-August Universität Göttingen
We study the dynamics of run-and-tumble particles on two-dimensional lattices, focusing on the effects of lattice geometry (square, triangular and hexagonal) and maximum occupation number nmax per lattice site. We identify three phases in the stationary state: a cluster (C) phase with extensive clusters formed by motility-induced phase separation, which appears only for nmax≥ 2; a gas (G) phase consisting of finite-sized clusters; and a new sponge (S) phase where small fluctuating clusters percolate. The nature of the transitions between these phases depend on lattice type and density. C-G transitions are mostly, but not always, first order, while C-S transitions are continuous. Single particle displacement distributions become non-Gaussian at higher densities, with intermediate exponential tails. Considering finally the transient dynamics from a random initial condition, the time it takes for clustering to appear in the system is independent of the tumble rate α but grows with the lattice coordination number and (exponentially or stronger) with nmax.