Structure of amorphous GeSe9 by neutron diffraction and first-principles molecular dynamics

impact of trajectory sampling and size effects

Sébastien Le Roux, Assil Bouzid, Kye Yeop Kim, Seungwu Han, Anita Zeidler, Philip S. Salmon, Carlo Massobrio

Research output: Contribution to journalArticle

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Abstract

The structure of glassy GeSe9 was investigated by combining neutron diffraction with density-functional theory-based first-principles molecular dynamics. In the simulations, three different models of N = 260 atoms were prepared by sampling three independent temporal trajectories, and the glass structures were found to be substantially different from those obtained for models in which smaller numbers of atoms or more rapid quench rates were employed. In particular, the overall network structure is based on Se_n chains that are cross-linked by Ge(Se4)1/2 tetrahedra, where the latter are predominantly corner as opposed to edge sharing. The occurrence of a substantial proportion of Ge-Se-Se connections does not support a model in which the material is phase separated into Se-rich and GeSe2-rich domains. The appearance of a first-sharp diffraction peak in the Bhatia Thornton concentration-concentration partial structure factor does,however,indicate a non-uniform distribution of the Ge-centered structural motifs on an intermediate length scale.
Original languageEnglish
Article number084502
Number of pages10
JournalJournal of Chemical Physics
Volume145
Issue number8
Early online date23 Aug 2016
DOIs
Publication statusPublished - 28 Aug 2016

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Neutron diffraction
neutron diffraction
Molecular dynamics
sampling
Trajectories
trajectories
molecular dynamics
Sampling
Atoms
tetrahedrons
Density functional theory
atoms
proportion
Diffraction
occurrences
density functional theory
Glass
glass
diffraction
simulation

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Structure of amorphous GeSe9 by neutron diffraction and first-principles molecular dynamics : impact of trajectory sampling and size effects. / Le Roux, Sébastien; Bouzid, Assil; Kim, Kye Yeop; Han, Seungwu; Zeidler, Anita; Salmon, Philip S.; Massobrio, Carlo.

In: Journal of Chemical Physics, Vol. 145, No. 8, 084502, 28.08.2016.

Research output: Contribution to journalArticle

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AU - Le Roux, Sébastien

AU - Bouzid, Assil

AU - Kim, Kye Yeop

AU - Han, Seungwu

AU - Zeidler, Anita

AU - Salmon, Philip S.

AU - Massobrio, Carlo

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AB - The structure of glassy GeSe9 was investigated by combining neutron diffraction with density-functional theory-based first-principles molecular dynamics. In the simulations, three different models of N = 260 atoms were prepared by sampling three independent temporal trajectories, and the glass structures were found to be substantially different from those obtained for models in which smaller numbers of atoms or more rapid quench rates were employed. In particular, the overall network structure is based on Se_n chains that are cross-linked by Ge(Se4)1/2 tetrahedra, where the latter are predominantly corner as opposed to edge sharing. The occurrence of a substantial proportion of Ge-Se-Se connections does not support a model in which the material is phase separated into Se-rich and GeSe2-rich domains. The appearance of a first-sharp diffraction peak in the Bhatia Thornton concentration-concentration partial structure factor does,however,indicate a non-uniform distribution of the Ge-centered structural motifs on an intermediate length scale.

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