Department of Chemistry and the Chicago Center for Theoretical Chemistry, James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
J Chem Phys. 2019 Dec 28;151(24):244504. doi: 10.1063/1.5130558.
We report studies of (i) the isothermal density dependent sequences of phases in two-dimensional systems of particles with repulsive pair potentials devised by Truskett [J. Chem. Phys. 145, 054901 (2016)] and Torquato [Phys. Rev. E 88, 042309 (2013)] to support a high-density Kagome lattice phase and (ii) transient structured fluctuations close to a transition to a Kagome lattice. The commonalities in the sequences of phases in these systems and other 2D systems suggest the existence of a universal mechanism driving all to favor similar packing arrangements as the density is increased, but the simulations also show that the only such general rule proposed, namely, the Süto theorem, is not a necessary condition for the support of multiple distinct lattice structures by a particular pair potential. The transient fluctuations in the liquid close to the liquid-to-Kagome phase transition have Kagome symmetry, whereas deeper in the liquid phase, the fluctuations have hexagonal symmetry. When the transition is string-to-Kagome phase, the transient structured fluctuations in the string phase have both six-fold and other than six-fold symmetries. The path of the string-to-Kagome transition in the Truskett system involves intermediate honeycomb configurations that subsequently buckle to form a Kagome lattice. The path of the string-to-Kagome transition in the Torquato system suggests that the Kagome phase is formed by coiled strings merging together; increasing density generates a Kagome phase with imperfections such as 8-particle rings.
我们报告了（i）由特鲁斯科特[J. Chem. Phys. 145, 054901 (2016)]和托夸托[Phys. Rev. E 88, 042309 (2013)]设计的具有排斥对势的二维粒子系统中等温密度相关相序列的研究，以支持高密度 Kagome 晶格相和（ii）接近 Kagome 晶格转变的瞬态结构涨落。这些系统和其他二维系统中相序列的共性表明，存在一种普遍的机制，促使所有系统都倾向于随着密度的增加而采用相似的堆积排列，但模拟也表明，唯一提出的此类一般规则，即 Süto 定理，并不是支持特定对势支持多种不同晶格结构的必要条件。接近液体到 Kagome 相转变的液体中的瞬态涨落具有 Kagome 对称性，而在液相更深的地方，涨落具有六边形对称性。当转变为弦到 Kagome 相时，弦相中的瞬态结构涨落具有六重和非六重对称性。特鲁斯科特系统中弦到 Kagome 转变的路径涉及中间的蜂窝状结构，随后这些结构弯曲形成 Kagome 晶格。托夸托系统中弦到 Kagome 转变的路径表明，Kagome 相是由螺旋弦合并形成的；增加密度会产生具有 8 粒子环等缺陷的 Kagome 相。
