Importance of many-body correlations in glass transition: An example from polydisperse hard spheres

Abstract

Most of the liquid-state theories, including glass-transition theories, are constructed on the basis of two-body density correlations. However, we have recently shown that many-body correlations, in particular, bond orientational correlations, play a key role in both the glass transition and the crystallization transition. Here we show, with numerical simulations of supercooled polydisperse hard spheres systems, that the length-scale associated with any two-point spatial correlation function does not increase toward the glass transition. A growing length-scale is instead revealed by considering many-body correlation functions, such as correlators of orientational order, which follows the length-scale of the dynamic heterogeneities. Despite the growing of crystal-like bond orientational order, we reveal that the stability against crystallization with increasing polydispersity is due to an increasing population of icosahedral arrangements of particles. Our results suggest that, for this type of systems, many-body correlations are a manifestation of the link between the vitrification and the crystallization phenomena. Whether a system is vitrified or crystallized can be controlled by the degree of frustration against crystallization, polydispersity in this case.

Observation of crystallization slowdown in supercooled parahydrogen and orthodeuterium quantum liquid mixtures

“…Similar results are found for all other simulated mixtures. As for the case of classical systems [28], we find that this tendency to noncrystalline order increases with the degree of supercooling. If a correlation between local order and crystal deposition rate could be established, then a difference in the packing efficiency for the two isotopic species as revealed by our structural analysis might provide a physical basis to explain the observed dependence of the crystal growth rate on the oD 2 mole fraction; the rearrangement of local noncrystalline structures in the supercooled melt at the liquid/crystal interface would tend to lower the particle diffusivity, thus slowing down the crystal growth [5].…”

“…A number of simulation studies [15,17,18,28] have suggested that in one possible scenario crystallization might be hindered by the emergence in the bulk supercooled liquid of locally preferred structures that eventually are incompatible with long-range crystalline order [34]. One important example is the icosahedron with its fivefold symmetry [35], which has been recently found to be a fundamental geometrical motif in the structure of bulk metallic glasses [36].…”

“…One important example is the icosahedron with its fivefold symmetry [35], which has been recently found to be a fundamental geometrical motif in the structure of bulk metallic glasses [36]. To explore this point we have performed a microscopic structural analysis based on the local bond order invariants method [4,18,28] of our simulated pH 2 -oD 2 mixtures. We have focused here on the invariant w 6 , which is most sensitive to icosahedral-like order, but the present analysis does not rule out the presence in the metastable liquid of local order with different symmetries.…”

“…As the next step we looked at the bulk structural features, which offer important insights into the behavior of supercooled liquids [4,15,17,28]. To access static structural properties of the nonequilibrium pH 2 -oD 2 quantum liquid mixtures we have carried out path-integral Monte Carlo (PIMC) simulations [29] by using a canonical [30] Worm algorithm [31].…”

Influence of Patch-Size Variability on the Crystallization of Tetrahedral Patchy Particles

“…For example, it is a well established result that perfectly monodisperse hard spheres are very good crystal formers, but increasing particle-size polydispersity gradually favors local icosahedral structures that turn the system into a glass former [15][16][17]. The first experimental realizations of hard-sphere crystals required significant effort, due to the high degree of monodispersity required [18].…”