Anisotropic pair correlations in binary and multicomponent hard-sphere mixtures in the vicinity of a hard wall: A combined density functional theory and simulation study.
Anisotropic pair correlations in binary and multicomponent hard-sphere mixtures in the vicinity of a hard wall: A combined density functional theory and simulation study.
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硬壁附近二元和多组分硬球混合物中的各向异性对相关性：密度泛函理论和模拟相结合的研究
DOI：
10.1103/physreve.92.042310
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M. Schmiedeberg
中科院分区：
文献类型：
--
作者：
A. Härtel;M. Kohl;M. Schmiedeberg
经典密度泛函理论的基本测度方法已被证明是预测硬球系统各种热力学性质的有力工具。我们采用这种方法不仅确定了在硬壁附近的二元和六组分硬球混合物中的单粒子密度，而且还确定了两粒子的相关性。破缺的各向同性使我们能够通过定量地比较布朗动力学模拟的结果，仔细地测试各种理论上预测的双粒子特征。具体来说，我们确定并比较了单粒子密度、总相关函数、它们的接触值和作用在粒子上的力分布。为此，我们遵循可压缩性路线，从理论上通过求函数导数来计算直接相关函数。我们通常在理论和模拟之间观察到非常好的一致性，除了在局部晶体状秩序出现的情况下的小偏差。我们的结果为进一步研究功能的一致性以及结构分析（例如，原始模型）奠定了基础。此外，我们证明了由于局部结晶的抑制，六组分混合物的预测比双分散或单分散系统的预测要好。最后，我们相信，我们的由壁引起的结构调制的结果导致了对各向异性系统中一般的有序、非均质结晶的开始、笼化效应、靠近壁的玻璃动力学以及约束系统中的结构特性的更深入的理解。
The fundamental measure approach to classical density functional theory has been shown to be a powerful tool to predict various thermodynamic properties of hard-sphere systems. We employ this approach to determine not only one-particle densities but also two-particle correlations in binary and six-component mixtures of hard spheres in the vicinity of a hard wall. The broken isotropy enables us to carefully test a large variety of theoretically predicted two-particle features by quantitatively comparing them to the results of Brownian dynamics simulations. Specifically, we determine and compare the one-particle density, the total correlation functions, their contact values, and the force distributions acting on a particle. For this purpose, we follow the compressibility route and theoretically calculate the direct correlation functions by taking functional derivatives. We usually observe an excellent agreement between theory and simulations, except for small deviations in cases where local crystal-like order sets in. Our results set the course for further investigations on the consistency of functionals as well as for structural analysis on, e.g., the primitive model. In addition, we demonstrate that due to the suppression of local crystallization, the predictions of six-component mixtures are better than those in bidisperse or monodisperse systems. Finally, we are confident that our results of the structural modulations induced by the wall lead to a deeper understanding of ordering in anisotropic systems in general, the onset of heterogeneous crystallization, caging effects, and glassy dynamics close to a wall, as well as structural properties in systems with confinement.