Department of Physics, Emory University, Atlanta, GA 30322, USA.
Bristol Centre for Functional Nanomaterials, Tyndall Avenue, Bristol BS8 1TL, UK.
Molecules. 2021 Mar 20;26(6):1746. doi: 10.3390/molecules26061746.
In the condensed liquid phase, both single- and multicomponent Lennard-Jones (LJ) systems obey the "hidden-scale-invariance" symmetry to a good approximation. Defining an isomorph as a line of constant excess entropy in the thermodynamic phase diagram, the consequent approximate isomorph invariance of structure and dynamics in appropriate units is well documented. However, although all measures of the structure are predicted to be isomorph invariant, with few exceptions only the radial distribution function (RDF) has been investigated. This paper studies the variation along isomorphs of the nearest-neighbor geometry quantified by the occurrence of Voronoi structures, Frank-Kasper bonds, icosahedral local order, and bond-orientational order. Data are presented for the standard LJ system and for three binary LJ mixtures (Kob-Andersen, Wahnström, NiY2). We find that, while the nearest-neighbor geometry generally varies significantly throughout the phase diagram, good invariance is observed along the isomorphs. We conclude that higher-order structural correlations are no less isomorph invariant than is the RDF.
在浓缩液相中，单组分和多组分 Lennard-Jones (LJ) 系统都很好地近似遵循“隐藏比例不变性”对称性。将同构体定义为热力学相图中过剩熵的常数线，适当单位下结构和动力学的相应近似同构不变性得到了很好的证明。然而，尽管所有结构的度量都被预测为同构不变，除了少数例外，只有径向分布函数 (RDF) 得到了研究。本文研究了通过 Voronoi 结构、Frank-Kasper 键、二十面体局部有序和键取向有序来量化的最近邻几何沿着同构体的变化。本文为标准 LJ 系统和三个二元 LJ 混合物（Kob-Andersen、Wahnström、NiY2）提供了数据。我们发现，虽然最近邻几何在整个相图中通常变化很大，但在同构体上观察到了很好的不变性。我们得出结论，高阶结构相关性与 RDF 一样具有同构不变性。
