Molecular dynamics and Monte Carlo methods are common measurements to study the diffusion coefficients of the fluid particles under restricted conditions. Here, the collective diffusion coefficient will be obtained through two methods: the one is Fick’s first law (direct mode), and the other is the relationship between collective diffusion coefficient and self-diffusion coefficient (indirect mode). A comparison between two methods is also discussed. The ways of calculation, which are applied for the self-diffusion coefficient and collective diffusion coefficient, are helpful for studying transport characteristics of various molecules in defined space.

Graphical abstract

In this manuscript, we have reported the collective diffusion coefficient obtained through two methods: Fick’s first law (direct mode, as shown in Fig. 1) and the relationship between collective diffusion coefficient and self-diffusion coefficient (indirect mode, as shown in Fig. 2). It is shown that the two methods are accessible and each has their advantages and disadvantages.

中文翻译：

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有限通道内的集体扩散系数：流体粒子的两种方法

分子动力学和蒙特卡罗方法是研究受限条件下流体粒子扩散系数的常用测量方法。这里，集体扩散系数将通过两种方法获得：一种是菲克第一定律（直接模式），另一种是集体扩散系数与自扩散系数的关系（间接模式）。还讨论了两种方法之间的比较。采用自扩散系数和集体扩散系数的计算方法，有助于研究各种分子在限定空间内的输运特性。

图形概要

在这篇手稿中，我们报道了通过两种方法获得的集体扩散系数：Fick 第一定律（直接模式，如图 1 所示）和集体扩散系数与自扩散系数的关系（间接模式，如图 1 所示）。 2). 事实表明，这两种方法都是可访问的，并且各有优缺点。