Dynamical fluctuation effects in glassy colloidal suspensions

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We provide here a brief perspective on the glass transition field. It is an assessment, written from the point of view of theory, of where the field is and where it seems to be heading. We first give an overview of the main phenomenological characteristics, or "stylised facts," of the glass transition problem, i.e., the central observations that a theory of the physics of glass formation should aim to explain in a unified manner. We describe recent developments, with a particular focus on real space properties, including dynamical heterogeneity and facilitation, the search for underlying spatial or structural correlations, and the relation between the thermal glass transition and athermal jamming. We then discuss briefly how competing theories of the glass transition have adapted and evolved to account for such real space issues. We consider in detail two conceptual and methodological approaches put forward recently, that aim to access the fundamental critical phenomenon underlying the glass transition, be it thermodynamic or dynamic in origin, by means of biasing of ensembles, of configurations in the thermodynamic case, or of trajectories in the dynamic case. We end with a short outlook.

Section: Stylised Facts Of the Glass Transitionmentioning

confidence: 99%

Section: A Non-exponential Relaxation In Time and Large Distributionmentioning

confidence: 99%

Section: 97mentioning

confidence: 99%

See 1 more Smart Citation

Perspective: The glass transition

Biroli

Garrahan

2013

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“…Departure from this relation, termed transport "decoupling" [25], is a manifestation of fluctuating, non mean-field, dynamics. Like in previous works [7,[26][27][28] we characterize the breakdown of the SER in terms of a "fractional" SER, D ∼ τ −1+ω , with ω > 0 encoding the degree of violation of the standard SER. We show that for the East model ω > 0, and therefore the relevance of dynamical fluctuations, for all dimensions between d = 1 and d = 10.…”

Section: Introductionmentioning

confidence: 99%

Study of the upper-critical dimension of the East model through the breakdown of the Stokes-Einstein relation

Kim

Thorpe

Noh

et al. 2017

We investigate the dimensional dependence of dynamical fluctuations related to dynamic heterogeneity in supercooled liquid systems using kinetically constrained models. The d-dimensional spinfacilitated East model with embedded probe particles is used as a representative super-Arrhenius glass forming system. We investigate the existence of an upper critical dimension in this model by considering decoupling of transport rates through an effective fractional Stokes-Einstein relation, D ∼ τ −1+ω , with D and τ the diffusion constant of the probe particle and the relaxation time of the model liquid, respectively, and where ω > 0 encodes the breakdown of the standard Stokes-Einstein relation. To the extent that decoupling indicates non mean-field behavior, our simulations suggest that the East model has an upper critical dimension which is at least above d = 10, and argue that it may be actually be infinite. This result is due to the existence of hierarchical dynamics in the East model in any finite dimension. We discuss the relevance of these results for studies of decoupling in high dimensional atomistic models.

“…[6][7][8][9][10][11][12][13][14][15] The origin of a spurious literal localization transition is the Gaussian-like assumption that dynamics is controlled by collective, but small and continuous, particle displacements. Large amplitude, highly non-Gaussian "aca) Electronic mail: kschweiz@illinois.edu.…”

Section: Introductionmentioning

confidence: 99%

Theory of correlated two-particle activated glassy dynamics: General formulation and heterogeneous structural relaxation in hard sphere fluids

Sussman

Schweizer

2011

We generalize the nonlinear Langevin equation theory of activated single particle dynamics to describe the correlated motion of two tagged spherical particles in a glass- or gel-forming fluid as a function of their initial separation. The theory is built on the concept of a two-dimensional dynamic free energy surface which quantifies the forces on two particles moving in a cooperative manner. For the hard sphere fluid, above a threshold volume fraction we generically find two relaxation channels corresponding largely, but not exclusively, to a center-of-mass-like displacement and a radial separation of the two tagged particles. The entropic barriers and mean first passage times are computed and found to systematically vary with volume fraction and initial particle separation; both oscillate as a function of the latter in a manner related to the equilibrium pair correlation function. A dynamic correlation length is estimated as the length scale beyond which the two-particle activated dynamics becomes uncorrelated in space and time, and is found to modestly grow with increasing mean relaxation time. The theory is also applied to a simplified model of cage escape, the elementary step of structural relaxation. Predictions for characteristic relaxation times, translation-relaxation decoupling, and stretched-exponential decay of time correlation functions are obtained. A novel mechanism for understanding why strong decoupling emerges in the activated regime, but stretched nonexponential time correlation functions do not change shape as the mean relaxation time grows, is presented and favorably compared with experiment. The theory may serve as a starting point for constructing a predictive model of multiple correlated caging and hopping (forward and backward) events of a pair of tagged particles.