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Physique Théorique
(61) Production(s) de l'année 2021
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Hunting for order in disordered systems 
Auteur(s): Kob W.
Conférence invité: Colloque de lancement MIPS (Montpellier, FR, 2021-11-08)
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On the structure of amorphous systems: More order than expected
Auteur(s): Kob W.
Conférence invité: Journées de la Matière Condensée 17 (Rennes, FR, 2021-08-24)
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On the structure of amorphous systems on intermediate and large length scales
Auteur(s): Kob W.
Conférence invité: Local structure meets machine learning in soft matter systems (Lausanne, CH, 2021-06-28)
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Nanocomposites and Gels: Insight from atomistic Simulations
Auteur(s): Kob W.
(Séminaires)
Institute of Natural Sciences, Shanghai Jiao Tong University (Shanghai, CN), 2021-05-18 |
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Percolation transitions in compressed SiO2 glasses
Auteur(s): Hasmy A., Ispas S., Hehlen B.
(Article) Publié:
Nature, vol. 599 p.62 (2021)
DOI: 10.1038/s41586-021-03918-0
Résumé: Amorphous–amorphous transformations under pressure are generally explained by
changes in the local structure from low- to higher-fold coordinated polyhedra1–4.
However, as the notion of scale invariance at the critical thresholds has not been
addressed, it is still unclear whether these transformations behave similarly to true
phase transitions in related crystals and liquids. Here we report ab initio-based
calculations of compressed silica (SiO2) glasses, showing that the structural changes
from low- to high-density amorphous structures occur through a sequence of
percolation transitions. When the pressure is increased to 82 GPa, a series of
long-range (‘infinite’) percolating clusters composed of corner- or edge-shared
tetrahedra, pentahedra and eventually octahedra emerge at critical pressures and
replace the previous ‘phase’ of lower-fold coordinated polyhedra and lower
connectivity. This mechanism provides a natural explanation for the well-known
mechanical anomaly around 3 GPa, as well as the structural irreversibility beyond
10 GPa, among other features. Some of the amorphous structures that have been
discovered mimic those of coesite IV and V crystals reported recently5,6, highlighting
the major role of SiO5 pentahedron-based polyamorphs in the densification process of
vitreous silica. Our results demonstrate that percolation theory provides a robust
framework to understand the nature and pathway of amorphous–amorphous
transformations and open a new avenue to predict unravelled amorphous solid states
and related liquid phases7,8.
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Cooperative excitations in superionic PbF2
Auteur(s): Mohn C. e., Krynski M., Kob W., Allen N. l.
(Article) Publié:
Philosophical Transactions Of The Royal Society Of London. Series A, Containing Papers Of A Mathematical Or Physical Character, vol. 379 p.20190455 (2021)
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