In: Journal of Statistical Mechanics: Theory and Experiment, 2019, vol. 2019, no. 6, p. 063203
We study the stochastic motion of a particle subject to spatially varying Lorentz force in the small-mass limit. The limiting procedure yields an additional drift term in the overdamped equation that cannot be obtained by simply setting mass to zero in the velocity Langevin equation. We show that whereas the overdamped equation of motion accurately captures the position statistics of the...
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In: Soft Matter, 2019, vol. 15, no. 6, p. 1319–1326
We study the phase transition dynamics of a fluid system in which the particles diffuse anisotropically in space. The motivation to study such a situation is provided by systems of interacting magnetic colloidal particles subject to the Lorentz force. The Smoluchowski equation for the many-particle probability distribution then acquires an anisotropic diffusion tensor. We show that in...
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In: The Journal of Chemical Physics, 2018, vol. 148, no. 19, p. 194116
In a theoretical and simulation study, active Brownian particles (ABPs) in three- dimensional bulk systems are exposed to time-varying sinusoidal activity waves that are running through the system. A linear response (Green-Kubo) formalism is applied to derive fully analytical expressions for the torque-free polarization profiles of non- interacting particles. The activity waves induce fluxes...
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In: Physical Review E, 2018, vol. 98, no. 1, p. 012601
Using overdamped Brownian dynamics simulations we investigate the isotropic- nematic (IN) transition of self-propelled rods in three spatial dimensions. For two well- known model systems (Gay-Berne potential and hard spherocylinders) we find that turning on activity moves to higher densities the phase boundary separating an isotropic phase from a (nonpolar) nematic phase. This active IN phase...
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In: Physical Review E, 2018, vol. 97, no. 1, p. 012601
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...
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In: Journal of Statistical Mechanics: Theory and Experiment, 2017, vol. 2017, no. 11, p. 113207
The equations of motion of active systems can be modeled in terms of Ornstein– Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should be approximated to yield a Markovian picture for the dynamics and a simplified steady-state condition. We perform a comparative study of the unified colored noise approximation (UCNA) and the approximation scheme...
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In: Physical Review E, 2017, vol. 96, no. 3, p. 032604
We generalize the Green-Kubo approach, previously applied to bulk systems of spherically symmetric active particles [J. Chem. Phys. 145, 161101 (2016)], to include spatially inhomogeneous activity. The method is applied to predict the spatial dependence of the average orientation per particle and the density. The average orientation is given by an integral over the self part of the Van Hove...
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In: Physical Review E, 2017, vol. 95, no. 1, p. 012115
The escape rate of a Brownian particle over a potential barrier is accurately described by the Kramers theory. A quantitative theory explicitly taking the activity of Brownian particles into account has been lacking due to the inherently out-of-equilibrium nature of these particles. Using an effective equilibrium approach [Farage et al., Phys. Rev. E 91, 042310 (2015)] we study the escape...
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In: Physical Review E, 2016, vol. 94, no. 4, p. 042407
Networks with only central force interactions are floppy when their average connectivity is below an isostatic threshold. Although such networks are mechanically unstable, they can become rigid when strained. It was recently shown that the transition from floppy to rigid states as a function of simple shear strain is continuous, with hallmark signatures of criticality [Sharma et al., Nature...
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In: The Journal of Chemical Physics, 2016, vol. 145, no. 16, p. 161101
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