Laboratoire Ondes et Matière d'Aquitaine (LOMA), CNRS, UMR 5798/Université de Bordeaux, F-33400 Talence, France.
Phys Rev E. 2017 Jan;95(1-1):012109. doi: 10.1103/PhysRevE.95.012109. Epub 2017 Jan 6.
We consider the time-dependent dispersion properties of overdamped tracer particles diffusing in a one-dimensional periodic potential under the influence of an additional constant tilting force F. The system is studied in the region where the force is close to the critical value F_{c} at which the barriers separating neighboring potential wells disappear. We show that, when F crosses the critical value, the shape of the mean-square displacement (MSD) curves is strongly modified. We identify a diffusive regime at intermediate-time scales with an effective diffusion coefficient which is much larger than the late-time diffusion coefficient for F>F_{c}, whereas for F<F_{c} the late-time and intermediate-time diffusive regimes are indistinguishable. Explicit asymptotic regimes for the MSD curves are identified at all time scales.
我们研究了在一维周期势中扩散的过阻尼示踪粒子的时变弥散特性，该势受到外加恒定倾斜力 F 的影响。在力接近使相邻势阱之间的势垒消失的临界值 F_{c}的区域中研究了该系统。我们表明，当 F 越过临界值时，均方位移（MSD）曲线的形状会发生强烈的改变。我们在中间时间尺度上识别出一个扩散区域，其有效扩散系数比 F>F_{c}时的后期扩散系数大得多，而对于 F<F_{c}，后期和中间时间扩散区域无法区分。在所有时间尺度上，MSD 曲线的显式渐近区域都被识别出来。
