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arXiv 1507.00484cond-mat.stat-mech
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硬核格子气中受驱示踪剂的位置分布

Distribution of the position of a driven tracer in a hardcore lattice gas

Pierre Illien, Olivier Bénichou, Gleb Oshanin, Raphaël Voituriez

摘要:

我们研究了一个有偏见的示踪粒子(TP)在一个浴的硬核粒子移动的任意尺寸的晶格和接触的水库。从TP位置和浴配置的联合概率所满足的主方程出发,并借助于平均场型近似,我们在先前的出版物[Phys. Rev. E \textbf{87},032164(2013)]中提出了TP位置的波动的计算。反直觉地,在一维晶格上,TP的扩散系数被示出为浴颗粒的密度的非单调函数,并且对于密度的非零值达到最大值。在这里,我们:(i)给出了计算的细节,并对扩散系数的非单调性的理解提供了物理上的理解;(ii)扩展了平均场型近似,使高阶关联函数解耦,并得到了TP位置的累积量母函数所满足的演化方程,该方程在任何空间维都有效。在一维格点的特殊情况下,我们求解这个方程,得到TP位置的概率分布。我们表明,重新调整的位置由其波动是渐近分布的高斯分布在长时间限制。

英文摘要:

We study the position of a biased tracer particle (TP) in a bath of hardcore particles moving on a lattice of arbitrary dimension and in contact with a reservoir. Starting from the master equation satisfied by the joint probability of the TP position and the bath configuration and resorting to a mean-field-type approximation, we presented a computation of the fluctuations of the TP position in a previous publication [Phys. Rev. E \textbf{87}, 032164 (2013)]. Counterintuitively, on a one-dimensional lattice, the diffusion coefficient of the TP was shown to be a non-monotonic function of the density of bath particles, and reaches a maximum for a nonzero value of the density. Here, we: (i) give the details of this computation and offer a physical insight into the understanding of the non-monotonicity of the diffusion coefficient; (ii) extend the mean-field-type approximation to decouple higher-order correlation functions, and obtain the evolution equation satisfied by the cumulant generating function of the position of the TP, valid in any space dimension. In the particular case of a one-dimensional lattice, we solve this equation and obtain the probability distribution of the TP position. We show that the position rescaled by its fluctuations is asymptotically distributed accordingly to a Gaussian distribution in the long-time limit.

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