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arXiv 1606.00641cond-mat.softcond-mat.stat-mech
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自推进粒子的非平衡玻璃态动力学

The nonequilibrium glassy dynamics of self-propelled particles

Elijah Flenner, Grzegorz Szamel, Ludovic Berthier

摘要:

我们研究玻璃态动力学发生在致密的组件的非热活性粒子,仅由非平衡自推进机制驱动。主动力被建模为一个Ornstein-Uhlenbeck随机过程,其特征在于持续时间和有效温度,和粒子通过一个Lennard-Jones潜在的,产生良好的研究在布朗极限的玻璃态行为的相互作用,获得的持续时间消失。通过增加的持续时间,系统更强烈地偏离热平衡,我们提供了一个全面的数值分析所产生的活性流体的结构和动力学。有限的持续时间深刻地影响流体的静态结构,并引起非平衡的速度相关性,在热系统中是不存在的。尽管这些非平衡功能,对于任何值的持续时间,我们观察到的非平衡玻璃化转变的有效温度降低。令人惊讶的是,增加偏离热平衡被发现促进(而不是抑制)的玻璃态动力学。总的来说,我们的研究结果表明,随着持续时间的增加,微观性质的活性流体的变化定量,但广泛的功能的非平衡态玻璃动力学观察到的有效温度降低定性相似的热玻璃形成。

英文摘要:

We study the glassy dynamics taking place in dense assemblies of athermal active particles that are driven solely by a nonequilibrium self-propulsion mechanism. Active forces are modeled as an Ornstein-Uhlenbeck stochastic process, characterized by a persistence time and an effective temperature, and particles interact via a Lennard-Jones potential that yields well-studied glassy behavior in the Brownian limit, obtained as the persistence time vanishes. By increasing the persistence time, the system departs more strongly from thermal equilibrium and we provide a comprehensive numerical analysis of the structure and dynamics of the resulting active fluid. Finite persistence times profoundly affect the static structure of the fluid and give rise to nonequilibrium velocity correlations that are absent in thermal systems. Despite these nonequilibrium features, for any value of the persistence time we observe a nonequilibrium glass transition as the effective temperature is decreased. Surprisingly, increasing departure from thermal equilibrium is found to promote (rather than suppress) the glassy dynamics. Overall, our results suggest that with increasing persistence time, microscopic properties of the active fluid change quantitatively, but the broad features of the nonequilibrium glassy dynamics observed with decreasing the effective temperature remain qualitatively similar to those of thermal glass-formers.

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