Bristol Centre for Complexity Sciences, University of Bristol, Bristol BS8 1TS, United Kingdom.
School of Mathematics, University of Bristol, University Walk, Bristol BS8 1TW, United Kingdom.
J Chem Phys. 2013 Dec 21;139(23):234505. doi: 10.1063/1.4830416.
Isomorphs are lines in the density-temperature plane of certain "strongly correlating" or "Roskilde simple" liquids where two-point structure and dynamics have been shown to be close to identical up to a scale transformation. Here we consider such a liquid, a Lennard-Jones glass former, and investigate the behavior along isomorphs of higher-order structural and dynamical correlations. We then consider an inverse power law reference system mapped to the Lennard-Jones system [Pedersen et al., Phys. Rev. Lett. 105, 157801 (2010)]. Using the topological cluster classification to identify higher-order structures, in both systems we find bicapped square antiprisms, which are known to be a locally favored structure in the Lennard-Jones glass former. The population of these locally favored structures is up to 80% higher in the Lennard-Jones system than the equivalent inverse power law system. The structural relaxation time of the two systems, on the other hand, is almost identical, and the four-point dynamical susceptibility is marginally higher in the inverse power law system. Upon cooling, the lifetime of the locally favored structures in the Lennard-Jones system is up to 40% higher relative to the reference system.
同构线是某些“强关联”或“罗西基德简单”液体的密度-温度平面中的线，在这些液体中，两点结构和动力学已经被证明在尺度变换下非常接近相同。在这里，我们考虑这样一种液体，一种 Lennard-Jones 玻璃形成体，并研究了同构线上更高阶结构和动力学相关性的行为。然后，我们考虑了映射到 Lennard-Jones 系统的逆幂律参考系统 [Pedersen 等人，Phys. Rev. Lett. 105, 157801 (2010)]。使用拓扑聚类分类来识别高阶结构，我们在两个系统中都发现了双帽正方形反棱柱，已知这是 Lennard-Jones 玻璃形成体中的局部有利结构。在 Lennard-Jones 系统中，这些局部有利结构的数量比等效的逆幂律系统高 80%。另一方面，两个系统的结构弛豫时间几乎相同，逆幂律系统的四点动力灵敏度略高。在冷却过程中，相对于参考系统，Lennard-Jones 系统中局部有利结构的寿命提高了 40%。
