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arXiv 1402.5253cond-mat.stat-mech
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动态环境中的移动性转型

Mobility transition in a dynamic environment

Urna Basu, Christian Maes

摘要:

取决于外部场$E$如何影响随机环境中粒子的动力学活动,它在中间$E$的微分迁移率可以变为负值。我们讨论的情况下,缓慢变化的随机环境中的驱动粒子显示负微分迁移率,而迁移率变成积极的更快的环境变化。我们说明了这种转变使用2D晶格洛伦兹模型中的粒子移动在一个简单的排斥步行者的背景。粒子的有效逃逸速率(或减去其碰撞频率)对粒子的迁移率行为至关重要,它既取决于$E$,也取决于排斥行走体的动力学速率$γ$。大$γ$,即,快速障碍物运动相当于仅仅用障碍物密度重新调整粒子的自由运动,而慢速障碍物动力学导致粒子运动与其自由运动更奇异地相关,并保持在$γ=0$中已经看到的负微分迁移率。在更一般的条款,我们也说明了使用一维随机游走,流动性过渡之间的时间尺度的准静态制度和流体的限制。

英文摘要:

Depending on how the dynamical activity of a particle in a random environment is influenced by an external field $E$, its differential mobility at intermediate $E$ can turn negative. We discuss the case where for slowly changing random environment the driven particle shows negative differential mobility while that mobility turns positive for faster environment changes. We illustrate this transition using a 2D-lattice Lorentz model where a particle moves in a background of simple exclusion walkers. The effective escape rate of the particle (or minus its collision frequency) which is essential for its mobility-behavior depends both on $E$ and on the kinetic rate $γ$ of the exclusion walkers. Large $γ$, i.e., fast obstacle motion, amounts to merely rescaling the particle's free motion with the obstacle density, while slow obstacle dynamics results in particle motion that is more singularly related to its free motion and preserves the negative differential mobility already seen at $γ=0$. In more general terms that we also illustrate using one-dimensional random walkers, the mobility transition is between the time-scales of the quasi-stationary regime and that of the fluid limit.

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