Glassy dynamics of athermal self-propelled particles: Computer simulations and a nonequilibrium microscopic theory

Szamel, Grzegorz; Flenner, Elijah

doi:10.1103/physreve.91.062304

Cited by 131 publications

(230 citation statements)

References 39 publications

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“…In the equilibrium fluid, such an interplay causes non-monotonic changes in the dynamics that lead to a reentrant melting of the glass [28,33]. Indeed, a similar reentrant behavior of the glassy dynamics of an active fluid (albeit not an ABP fluid) has been discussed [34]. It should, however, be stressed that the effective-attraction description of S(q) does not acknowledge the non-equilibrium nature of the active fluid.…”

Section: Discussionmentioning

confidence: 98%

Static structure of active Brownian hard disks

Biniossek

Löwen

Voigtmann

et al. 2018

J. Phys.: Condens. Matter

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Abstract. We explore the changes in static structure of a two-dimensional system of active Brownian particles (ABP) with hard-disk interactions, using event-driven Brownian dynamics simulations. In particular, the effect of the selfpropulsion velocity and the rotational diffusivity on the orientationally-averaged fluid structure factor is discussed. Typically activity increases structural ordering and generates a structure factor peak at zero wave vector which is a precursor of motility-induced phase separation. Our results provide reference data to test future statistical theories for the fluid structure of active Brownian systems.

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Section: Discussionmentioning

confidence: 98%

Static structure of active Brownian hard disks

Biniossek

Löwen

Voigtmann

et al. 2018

J. Phys.: Condens. Matter

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“…This is a direct consequence of the form of Eq. (36). The colored lines for D (1) a = 4.8 and for all parameters being equal (ep) are the same as in Fig.…”

Section: Model Calculationsmentioning

confidence: 91%

“…The model of active particles propelled by so-called Ornstein-Uhlenbeck processes (OUPs) provides a convenient starting point of many theoretical studies [34][35][36][37][38][39], since their equations of motion do not resolve the orientational degrees of freedom. A minimalistic strategy is based on the multidimensional generalizations of the unified colored noise approximation (UCNA) [40,41] or a similar approach by Fox [42,43]; see Ref.…”

Section: Introductionmentioning

confidence: 99%

Effective equilibrium states in mixtures of active particles driven by colored noise

et al. 2018

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We consider the steady-state behavior of pairs of active particles having different persistence times and diffusivities. To this purpose we employ the active Ornstein-Uhlenbeck model, where the particles are driven by colored noises with exponential correlation functions whose intensities and correlation times vary from species to species. By extending Fox's theory to many components, we derive by functional calculus an approximate Fokker-Planck equation for the configurational distribution function of the system. After illustrating the predicted distribution in the solvable case of two particles interacting via a harmonic potential, we consider systems of particles repelling through inverse power-law potentials. We compare the analytic predictions to computer simulations for such soft-repulsive interactions in one dimension and show that at linear order in the persistence times the theory is satisfactory. This work provides the toolbox to qualitatively describe many-body phenomena, such as demixing and depletion, by means of effective pair potentials.

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“…The model does not include more complex features such as alignment rules or hydrodynamic interactions and serves as a minimal model to study the direct competition between glassiness and self-propulsion. A continuous-time version of the model for arbitrary particle interactions has recently appeared [35].…”

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confidence: 99%

From single-particle to collective effective temperatures in an active fluid of self-propelled particles

Levis¹,

Berthier²

2015

EPL

Self Cite

101

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-We present a comprehensive analysis of effective temperatures based on fluctuationdissipation relations in a model of an active fluid composed of self-propelled hard disks. We first investigate the relevance of effective temperatures in the dilute and moderately dense fluids. We find that a unique effective temperature does not in general characterize the non-equilibrium dynamics of the active fluid over this broad range of densities, because fluctuation-dissipation relations yield a lengthscale-dependent effective temperature. By contrast, we find that the approach to a non-equilibrium glass transition at very large densities is accompanied by the emergence of a unique effective temperature shared by fluctuations at all lengthscales. This suggests that an effective thermal dynamics generically emerges at long times in very dense suspensions of active particles due to the collective freezing occurring at non-equilibrium glass transitions.Introduction. -Statistical mechanics provides a unified theoretical description of systems at thermal equilibrium in terms of the probability distribution over phase space, from which thermodynamic quantities such as temperature can be defined [1]. A similar framework is lacking for out-of-equilibrium systems for which the definition of a temperature remains an open issue [2]. Active matter formed by assemblies of living cells [3], bacteria [4], selfpropelled colloids [5][6][7][8] or grains [9,10], is a coherent class of non-equilibrium systems receiving increasing attention, because they raise fundamental issues and for potential applications in soft matter and biophysics [11,12]. A number of recent studies have addressed the question of whether "effective" thermodynamic concepts can be fruitfully applied to describe the phase behaviour and microscopic dynamics of active matter. This question is natural because if some mapping to an equilibrium situation exists, then the whole arsenal of equilibrium statistical mechanics becomes available for further theoretical treatment. In particular the definition of a non-equilibrium temperature [13][14][15][16][17][18], of an active pressure [8,19,20], of activityinduced interactions [8,21] and non-equilibrium free energies [22,23] have been investigated for self-propelled particles.

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Glassy dynamics of athermal self-propelled particles: Computer simulations and a nonequilibrium microscopic theory

Cited by 131 publications

References 39 publications

Static structure of active Brownian hard disks

Static structure of active Brownian hard disks

Effective equilibrium states in mixtures of active particles driven by colored noise

From single-particle to collective effective temperatures in an active fluid of self-propelled particles

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