The Glassy Solid as a Statistical Ensemble of Crystalline Microstates

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 diffractio...

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Bibliographic Details
Published in:arXiv.org 2019-02
Main Authors: Jones, Eric B, Stevanovic, Vladan
Format: Article
Language:English
Subjects:
Amorphous silicon
Crystal structure
Crystallinity
Distribution functions
Ergodic processes
First principles
Photovoltaic cells
Potential energy
Radial distribution
Silica glass
Silicon dioxide
X ray powder diffraction
X-ray diffraction
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Summary: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.
ISSN:2331-8422