International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy.
Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047, Japan.
J Phys Chem B. 2023 Apr 13;127(14):3302-3311. doi: 10.1021/acs.jpcb.2c09009. Epub 2023 Mar 31.
Topological data analysis (TDA) is a newly emerging and powerful tool for understanding the medium-range structure ordering of multiscale data. This study investigates the density anomalies observed during the cooling of liquid silica from a topological point of view using TDA. The density of liquid silica does not monotonically increase during cooling; it instead shows a maximum and minimum. Despite tremendous efforts, the structural origin of these density anomalies is not clearly understood. Our approach reveals that the one-dimensional topology of the -Si-Si- network changes at the temperatures at which the maximum and minimum densities are observed in our MD simulations, while those of the -O-O- and -Si-O- networks change at lower temperatures. Our ring analysis motivated by the TDA outcomes reveals that quantitative changes in -Si-Si- rings occur at the temperatures where the density is maximized and minimized, while those of the -O-O- and -Si-O- rings occur at lower temperatures; such findings are perfectly consistent with our TDA results. Our work demonstrates the value of new topological techniques in understanding the transitions in glassy materials and sheds light on the characterization of glass-liquid transitions.
拓扑数据分析（TDA）是一种新兴的强大工具，可用于理解多尺度数据的中程结构排序。本研究从拓扑学的角度研究了液体二氧化硅冷却过程中观察到的密度异常。液体二氧化硅的密度在冷却过程中不是单调增加的，而是会出现最大值和最小值。尽管付出了巨大的努力，但这些密度异常的结构起源仍不清楚。我们的方法表明，在我们的 MD 模拟中观察到最大和最小密度的温度下，-Si-Si-网络的一维拓扑发生了变化，而-O-O-和-Si-O-网络的拓扑则在较低的温度下发生了变化。受 TDA 结果启发的环分析表明，-Si-Si-环的定量变化发生在密度最大和最小的温度下，而-O-O-和-Si-O-环的变化则发生在较低的温度下；这些发现与我们的 TDA 结果完全一致。我们的工作证明了新的拓扑技术在理解玻璃材料转变方面的价值，并为玻璃-液体转变的特征提供了线索。
