Nonequilibrium mode-coupling theory for dense active systems of self-propelled particles

Abstract

The physics of active systems of self-propelled particles, in the regime of a dense liquid state, is an open puzzle of great current interest, both for statistical physics and because such systems appear in many biological contexts. We develop a nonequilibrium mode-coupling theory (MCT) for such systems, where activity is included as a colored noise with the particles having a self-propulsion foce $f_0$ and persistence time ${\tau }_p$. Using the extended MCT and a generalized fluctuation-dissipation theorem, we calculate the effective temperature $T_{eff}$ of the active fluid. The nonequilibrium nature of the systems is manifested through a time-dependent $T_{eff}$ that approaches a constant in the long-time limit, which depends on the activity parameters $f_0$ and ${\tau }_p$. We find, phenomenologically, that this long-time limit is captured by the potential energy of a single, trapped active particle (STAP). Through a scaling analysis close to the MCT glass transition point, we show that ${\tau }_{\alpha }$, the $\alpha$-relaxation time, behaves as ${\tau }_{\alpha }\sim f_0^{-2\gamma }$, where $\gamma =1.74$ is the MCT exponent for the passive system. ${\tau }_{\alpha }$ may increase or decrease as a function of ${\tau }_p$ depending on the type of active force correlations, but the behavior is always governed by the same value of the exponent $\gamma$. Comparison with numerical solution of the nonequilibrium MCT as well as simulation results give excellent agreement with the scaling analysis.

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Cited by in corpus (8)

• Perspective: Nonequilibrium glassy dynamics in dense systems of active particles
• Mode-Coupling Theory for Active Brownian Particles
• Effects of active fluctuations on energetics of a colloidal particle: superdiffusion, dissipation and entropy production
• Escape of a passive particle from activity-induced energy landscape: Emergence of slow and fast effective diffusion
• Mode-coupling theory for the steady-state dynamics of active Brownian particles
• Reconfiguration, swelling and tagged monomer dynamics of a single polymer chain in Gaussian and non-Gaussian active baths
• Scaling equations for mode-coupling theories with multiple decay channels
• Tagged-particle motion in quasi-confined colloidal hard-sphere liquids