Characterization of MIPS in a suspension of repulsive active Brownian particles through dynamical features



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Martín Roca, José and Martínez, Raúl and Alexander, Lachlan C. and Díez, Ángel Luis and Aarts, Dirk G. A. L. and Alarcón, Francisco and Ramírez, Jorge and Valeriani, Chantal (2021) Characterization of MIPS in a suspension of repulsive active Brownian particles through dynamical features. Journal of chemical physics, 154 (16). ISSN 0021-9606

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We study a two-dimensional system composed by Active Brownian Particles (ABPs), focusing on the onset of Motility Induced Phase Separation (MIPS), by means of molecular dynamics simulations. For a pure hard-disk system with no translational diffusion, the phase diagram would be completely determined by their density and Peclet number. In our model, two additional effects are present: translational noise and the overlap of particles; we study the effects of both in the phase space. As we show, the second effect can be mitigated if we use, instead of the standard Weeks-Chandler-Andersen potential, a stiffer potential: the pseudo-hard sphere potential. Moreover, in determining the boundary of our phase space, we explore different approaches to detect MIPS and conclude that observing dynamical features, via the non-Gaussian parameter, is more efficient than observing structural ones, such as through the local density distribution function. We also demonstrate that the Vogel-Fulcher equation successfully reproduces the decay of the diffusion as a function of density, with the exception of very high densities. Thus, in this regard, the ABP system behaves similar to a fragile glass.

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The authors acknowledge funding from the MINECO and the UCM/Santander PR26/16-10B-2 under Grant Nos. FIS2016-78847-P and ID2019-105343GB-I00, respectively. F.A. acknowledges support from the "Juan de la Cierva" program (No. FJCI-2017-33580). R.M. acknowledges funding from the MICINN (Ministerio de Ciencia e Innovacion, Spain, FPI Grant No. BES-2017-081108). The authors acknowledge the computer resources and technical assistance provided by the Centro de Supercomputacion y Visualización de Madrid (CeSViMa) and the Red Española de Supercomputación (RES, Grant Nos. FI-2020-1-0015 and FI-2020-2-0032). There are no conflicts to declare.

Uncontrolled Keywords:Chemistry, Physical; Physics, Atomic, Molecular & Chemical
Subjects:Sciences > Physics > Nuclear physics
ID Code:70523
Deposited On:22 Feb 2022 08:22
Last Modified:22 Apr 2022 22:00

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