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arXiv 1902.05939cond-mat.mtrl-sci
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玻璃态固体作为晶体微观态的统计集合

The Glassy Solid as a Statistical Ensemble of Crystalline Microstates

Eric B. Jones, Vladan Stevanovic

摘要:

出于部分遍历性的概念,我们提出了一种替代的描述共价和离子的玻璃态固体的统计合奏的结晶局部极小值的势能面。我们分析表明,径向分布函数(RDF)和粉末X射线衍射(XRD)强度的遍历系统可以严格制定为统计系综平均值,我们评估非晶硅和玻璃态二氧化硅通过第一原理随机结构采样。我们表明,使用具有小至24个原子的晶胞的结构,我们能够准确地复制非晶硅的实验RDF和XRD图案以及玻璃态二氧化硅的关键结构特征,从而支持玻璃的整体性质,并打开大门,完全预测描述而不需要实验输入。

英文摘要:

Motivated by the concept of partial ergodicity, we present an alternative description of covalent and ionic glassy solids as statistical ensembles of crystalline local minima on the potential energy surface. We show analytically that the radial distribution function (RDF) and powder X-ray diffraction (XRD) intensity of ergodic systems can be rigorously formulated as statistical ensemble averages, which we evaluate for amorphous silicon and glassy silica through the first-principles random structure sampling. We show that using structures with unit cells as small as 24 atoms, we are able to accurately replicate the experimental RDF and XRD pattern for amorphous silicon as well as the key structural features for glassy silica, thus supporting the ensemble nature of the glasses and opening the door to fully predictive description without the need for experimental inputs.

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