arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1912.03425cond-mat.stat-mech
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主动运动的广义持续动力学

Generalized persistence dynamics for active motion

Francisco J. Sevilla, Pavel Castro-Villarreal

摘要:

我们分析了统计物理的自推进粒子从一般的理论框架,适当地描述了最显着的特点,积极的运动,$persistence$,在任意的空间维度。这样一个框架允许在给定的位置和时间找到粒子的概率密度的Smoluchowski方程的发展,而不像基于Langevin方程的模型那样假设自推进速度的显式方向动力学。此外,布朗运动由于热涨落和积极的一个由于一般的固有的持续运动的粒子被考虑在平等的基础上。在我们的形式体系中,运动的持续性以\emph{two-time memory function},$K(t,t^{\prime})$的形式引入。我们专注于后果时,$K(t,t^{\prime})\sim (t/t^{\prime})^{-η}\exp[-Γ(t-t^{\prime})]$,$Γ$的特征持续时间,并表明它精确地描述了各种积极的运动模式,其特征在于$η$。我们发现实验获得的中间散射函数,均方位移的时间依赖性,和峰度的解析表达式。

英文摘要:

We analyze the statistical physics of self-propelled particles from a general theoretical framework that properly describes the most salient characteristic of active motion, $persistence$, in arbitrary spatial dimensions. Such a framework allows the development of a Smoluchowski-like equation for the probability density of finding a particle at a given position and time, without assuming an explicit orientational dynamics of the self-propelling velocity as Langevin-like equation-based models do. Also, the Brownian motion due to thermal fluctuations and the active one due to a general intrinsic persistent motion of the particle are taken into consideration on an equal footing. The persistence of motion is introduced in our formalism in the form of a \emph{two-time memory function}, $K(t,t^{\prime})$. We focus on the consequences when $K(t,t^{\prime})\sim (t/t^{\prime})^{-η}\exp[-Γ(t-t^{\prime})]$, $Γ$ being the characteristic persistence time, and show that it precisely describes a variety of active motion patterns characterized by $η$. We find analytical expressions for the experimentally obtainable intermediate scattering function, the time dependence of the mean-squared displacement, and the kurtosis.

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