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Short range order and network connectivity in amorphous AsTe3: a first principles, machine learning, and XRD study
Gaëlle Delaizir,Andrea Piarristeguy,Annie Pradel,Olivier Masson,Assil Bouzid
Physical Chemistry Chemical Physics Pub Date : 09/17/2020 00:00:00 , DOI:10.1039/D0CP03383A
Abstract

The atomic scale structure of amorphous AsTe3 is investigated through X-ray diffraction, first-principles molecular dynamics (FPMD), and machine learning interatomic potentials (ML-GAP) obtained by exploiting the ab initio data. We obtain good agreement between the measured and modelled diffraction patterns. Our FPMD results show that As and Te obey the 8-N rule with average coordination numbers of 3 and 2, respectively. We find that small fractions of under and over coordinated As and Te atoms are present in the amorphous phase with about 6% (FPMD), and 13% (ML-GAP) of 3-fold Te. As is found at the center of pyramidal structures predominantly linked through Ten chains rather than rings. Despite the low As concentration in AsTe3, its local environment features a very high chemical disorder that manifests through the occurrence of homopolar bonds including at least 57% of As atoms.

Graphical abstract: Short range order and network connectivity in amorphous AsTe3: a first principles, machine learning, and XRD study
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