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arXiv 1002.0273cond-mat.stat-mechcond-mat.soft
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相互作用布朗粒子系统中的非对称排斥过程

Asymmetric Exclusion Process in a System of Interacting Brownian Particles

Jose Eduardo de Oliveira Rodrigues, Ronald Dickman

摘要:

我们研究了一个连续空间版本的完全不对称简单排斥过程(TASEP),由相互作用的布朗粒子在周期性的外部势的驱动力。粒子以$α$的速率插入最左边的位点,以单位速率跳到右边,并以$β$的速率从最右边的位点移除。我们的研究动机是最近的实验胶体粒子在光镊阵列。外部电势的形式由这样的阵列产生。粒子大部分时间都在势能极小值附近,近似于格子气中的情况;短程排斥相互作用阻止两个粒子占据同一个势阱。一个恒定的驱动力,代表斯托克斯阻力的颗粒悬浮在一个移动的流体,导致偏置运动。通过数值积分的朗之万方程和动态蒙特卡罗模拟,我们的结果得到的密度分布和电流,表明连续空间模型表现出类似于在晶格模型中观察到的相变。然而,由于我们的模型中缺乏粒子-空穴对称性,这种对应并不精确。

英文摘要:

We study a continuous-space version of the totally asymmetric simple exclusion process (TASEP), consisting of interacting Brownian particles subject to a driving force in a periodic external potential. Particles are inserted at the leftmost site at rate $α$, hop to the right at unit rate, and are removed at the rightmost site at rate $β$. Our study is motivated by recent experiments on colloidal particles in optical tweezer arrays. The external potential is of the form generated by such an array. Particles spend most of the time near potential minima, approximating the situation in the lattice gas; a short-range repulsive interaction prevents two particles from occupying the same potential well. A constant driving force, representing Stokes drag on particles suspended in a moving fluid, leads to biased motion. Our results for the density profile and current, obtained via numerical integration of the Langevin equation and dynamic Monte Carlo simulations, indicate that the continuous-space model exhibits phase transitions analogous to those observed in the lattice model. The correspondence is not exact, however, due to the lack of particle-hole symmetry in our model.

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