The glassy solid as a statistical ensemble of crystalline microstates
The glassy solid as a statistical ensemble of crystalline microstates
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DOI：
10.1038/s41524-020-0329-2
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发表时间：
2020-05-14
影响因子：
9.7
通讯作者：
Stevanovic, Vladan
中科院分区：
文献类型：
--
作者：
Jones, Eric B.;Stevanovic, Vladan
我们提出了一种替代方案，并为非结晶材料设计的目的，一个更合适的描述共价和离子的玻璃态固体作为统计合奏的结晶局部极小值的势能面。出于部分破碎遍历性的概念，我们解析地制定了一套近似下，遍历系统的结构特征，如径向分布函数（RDF）和粉末X射线衍射（XRD）强度可以严格表示为统计系综平均在不同的局部极小值。通过评估这些元素Si和SiO2的整体平均值进行验证，通过我们使用相对较小的模拟单元进行的第一原理随机结构采样获得局部最小值，从而将采样限制在一组主要是晶体结构。实验（非晶硅）和分子动力学模拟（玻璃态SiO2）的XRD和RDF的比较显示出极好的一致性，从而支持了玻璃的系综图，并打开了完全预测描述的大门，而无需实验输入。
We present an alternative and, for the purpose of non-crystalline materials design, a more suitable description of covalent and ionic glassy solids as statistical ensembles of crystalline local minima on the potential energy surface. Motivated by the concept of partially broken ergodicity, we analytically formulate the set of approximations under which the structural features of ergodic systems such as the radial distribution function (RDF) and powder X-ray diffraction (XRD) intensity can be rigorously expressed as statistical ensemble averages over different local minima. Validation is carried out by evaluating these ensemble averages for elemental Si and SiO2 over the local minima obtained through the first-principles random structure sampling that we performed using relatively small simulation cells, thereby restricting the sampling to a set of predominantly crystalline structures. The comparison with XRD and RDF from experiments (amorphous silicon) and molecular dynamics simulations (glassy SiO2) shows excellent agreement, thus supporting the ensemble picture of glasses and opening the door to fully predictive description without the need for experimental inputs.