Transport and fluctuation-dissipation relations in asymptotic and preasymptotic diffusion across channels with variable section.
Transport and fluctuation-dissipation relations in asymptotic and preasymptotic diffusion across channels with variable section.
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跨可变截面通道的渐近和渐近前扩散中的传输和波动耗散关系。
DOI：
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
A. Vulpiani
中科院分区：
文献类型：
--
作者：
Giuseppe Forte;F. Cecconi;A. Vulpiani
研究了布朗粒子在空间周期性变化的通道中的渐近和预渐近扩散性质。有效扩散系数D(Jeff)是由不同几何形状的均方根位移的渐近行为决定的，甚至考虑了通道边界陡峭变化的情况。此外，我们将数值结果与文献中提出的对著名的Fick-Jacobs近似的各种修正的预测进行了比较。建立了有效的一维纵向扩散方程，得到了有效扩散系数的近似解。这样的结果超越了摄动法，与数值模拟得到的实际值吻合得很好。我们还讨论了预渐近扩散，它的值在通道横截面存在强烈空间变化的情况下可能很大，直到一个交叉时间。此外，我们还证明了小外场引起的平均漂移与未扰动系统的均方位移之间的爱因斯坦关系在渐近区和预渐近区都是有效的。
We study the asymptotic and preasymptotic diffusive properties of Brownian particles in channels whose section varies periodically in space. The effective diffusion coefficient D(eff) is numerically determined by the asymptotic behavior of the root mean square displacement in different geometries, considering even cases of steep variations of the channel boundaries. Moreover, we compared the numerical results to the predictions from the various corrections proposed in the literature to the well known Fick-Jacobs approximation. Building an effective one-dimensional equation for the longitudinal diffusion, we obtain an approximation for the effective diffusion coefficient. Such a result goes beyond a perturbation approach, and it is in good agreement with the actual values obtained by the numerical simulations. We discuss also the preasymptotic diffusion which is observed up to a crossover time whose value, in the presence of strong spatial variation of the channel cross section, can be very large. In addition, we show how the Einstein's relation between the mean drift induced by a small external field and the mean square displacement of the unperturbed system is valid in both asymptotic and preasymptotic regimes.
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有死角的管中的瞬时扩散。
DOI：
10.1063/1.2805068
发表时间：
2007
期刊：
The Journal of chemical physics
影响因子：
--
作者：
Dagdug,Leonardo;Berezhkovskii,AlexanderM;Makhnovskii,YuriiA;Zitserman,VladimirYu
通讯作者：
Zitserman,VladimirYu
影响因子：
4.4
作者：
Berezhkovskii, A. M.;Pustovoit, M. A.;Bezrukov, S. M.
通讯作者：
Bezrukov, S. M.
影响因子：
3.4
作者：
Heng, JB;Ho, C;Timp, G
通讯作者：
Timp, G
影响因子：
56.9
作者：
Han, J;Craighead, HG
通讯作者：
Craighead, HG