Understanding fragility in supercooled Lennard-Jones mixtures. I. Locally preferred structures.
The existence of systematic variations of isobaric fragility in different supercooled Lennard-Jones binary mixtures is revealed by molecular dynamics simulations. The connection between fragility and local structures in the bulk is analyzed by means of a Voronoi construction. It is found that clusters of particles belonging to locally preferred structures form slow, long-lived domains, whose spatial extension increases with decreasing temperature. As a general rule, a more rapid growth, upon supercooling, of such domains is associated with a more pronounced super-Arrhenius behavior, and hence to a larger fragility.
Coslovich
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Dipartimento di Fisica Teorica, Università di Trieste--Strada Costiera 11, 34100 Trieste, Italy.
Pastore
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