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Transport coefficients in dense active Brownian particle systems: mode-coupling theory and simulation results

Reichert, Julian and Granz, Leon F. and Voigtmann, Thomas (2021) Transport coefficients in dense active Brownian particle systems: mode-coupling theory and simulation results. European Physical Journal E, 44, p. 27. Springer. doi: 10.1140/epje/s10189-021-00039-4. ISSN 1292-8941.

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We discuss recent advances in developing a mode-coupling theory of the glass transition (MCT) of two-dimensional systems of active Brownian particles (ABPs). The theory describes the structural relaxation close to the active glass in terms of transient dynamical density correlation functions. We summarize the equations of motion that have been derived for the collective density-fluctuation dynamics and those for the tagged-particle motion. The latter allow to study the dynamics of both passive and active tracers in both passive and active host systems. In the limit of small wave numbers, they give rise to equations of motion describing the mean-squared displacements (MSDs) of these tracers and hence the long-time diffusion coefficients as a transport coefficient quantifying long-range tracer motion. We specifically discuss the case of a single ABP tracer in a glass-forming passive host suspension, a case that has recently been studied in experiments on colloidal Janus particles. We employ event-driven Brownian dynamics (ED-BD) computer simulations to test the ABP-MCT and find good agreement between the two for the MSD, provided that known errors in MCT already for the passive system (i.e., an overestimation of the glassiness of the system) are accounted for by an empirical mapping of packing fractions and host-system self-propulsion forces. The ED-BD simulation results also compare well to experimental data, although a peculiar non-monotonic mapping of self-propulsion velocities is required. The ABP-MCT predicts a specific self-propulsion dependence of the Stokes–Einstein relation between the long-time diffusion coefficient and the host-system viscosity that matches well the results from simulation. An application of ABP-MCT within the integration-through transients framework to calculate the density-renormalized effective swim velocity of the interacting ABP agrees qualitatively with the ED-BD simulation data at densities close to the glass transition and quantitatively for the full density range only after the mapping of packing fractions employed for the passive system.

Item URL in elib:https://elib.dlr.de/141375/
Document Type:Article
Title:Transport coefficients in dense active Brownian particle systems: mode-coupling theory and simulation results
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Date:11 March 2021
Journal or Publication Title:European Physical Journal E
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:p. 27
Keywords:active matter, mode coupling theory, motility induced phase separation, nonequilibrium transport coefficients
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Material Design and New Materials
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space
Deposited By: Voigtmann, Dr.rer.nat. Thomas
Deposited On:23 Mar 2021 08:54
Last Modified:05 Dec 2023 08:16

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