Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Mexico, 09340 Distrito Federal, Mexico.
J Chem Phys. 2012 Jun 7;136(21):214110. doi: 10.1063/1.4726193.
We investigate transport of point Brownian particles in a tube formed by identical periodic compartments of varying diameter, focusing on the effects due to the compartment asymmetry. The paper contains two parts. First, we study the force-dependent mobility of the particle. The mobility is a symmetric non-monotonic function of the driving force, F, when the compartment is symmetric. Compartment asymmetry gives rise to an asymmetric force-dependent mobility, which remains non-monotonic when the compartment asymmetry is not too high. The F-dependence of the mobility becomes monotonic in tubes formed by highly asymmetric compartments. The transition of the F-dependence of the mobility from non-monotonic to monotonic behavior results in important consequences for the particle motion under the action of a time-periodic force with zero mean, which are discussed in the second part of the paper: In a tube formed by moderately asymmetric compartments, the particle under the action of such a force moves with an effective drift velocity that vanishes at small and large values of the force amplitude having a maximum in between. In a tube formed by highly asymmetric compartments, the effective drift velocity monotonically increases with the amplitude of the driving force and becomes unboundedly large as the amplitude tends to infinity.
我们研究了点布朗粒子在由不同直径的相同周期性隔室组成的管中的输运，重点研究了隔室不对称引起的影响。本文包含两部分。首先，我们研究了粒子的力相关迁移率。当隔室对称时，迁移率是驱动力 F 的对称非单调函数。隔室不对称会导致不对称的力相关迁移率，当隔室不对称不太高时，它仍然是非单调的。当由高度不对称的隔室形成的管时，迁移率对 F 的依赖性变为单调。迁移率对 F 的依赖性从非单调到单调行为的转变对在具有零均值的时变周期性力作用下的粒子运动产生了重要的后果，这在本文的第二部分进行了讨论：在由中等不对称隔室形成的管中，在这种力的作用下，粒子以有效漂移速度运动，该速度在力幅度较小时和较大时为零，在中间有最大值。在由高度不对称隔室形成的管中，有效漂移速度随驱动力幅度单调增加，并随着幅度趋于无穷大而变得无界大。
