Cluster structure and dynamics in gels and glasses

Pastore, Raffaele; Candia, A. de; Fierro, Annalisa; Ciamarra, Massimo Pica; Coniglio, Antonio

doi:10.1088/1742-5468/2016/07/074011

Cited by 4 publications

(5 citation statements)

References 56 publications

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“…In those papers, the authors considered the m = 2 KA model on a square twodimensional lattice with periodic boundary conditions on all sides, but with a homogeneous applied field in the x direction, such that a particle moves in the negative x direction with a lower probability than in the other three directions. In the extreme case in which the particle cannot move against the field, the average current is given by (14) which in the steady state under the no correlations approximation may be expressed using the diffusion coefficient…”

Section: A Kob-andersen Modelmentioning

confidence: 99%

“…By construction, the equilibrium state of these models is trivial. However their dynamics are cooperatively slow and they exhibit many hallmarks of glassy systems, such as dynamical heterogeneities [3][4][5][6][7][8][9][10][11][12][13][14], nonexponential relaxation [8][9][10][11][12][13][14][15][16][17][18][19][20], and ageing [21][22][23], and in certain situations may exhibit an ergodicity-breaking jamming transition, beyond which a finite fraction of the particles are permanently frozen [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamics in kinetically constrained lattice-gas models

Teomy

Shokef

2017

Phys. Rev. E

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Kinetically constrained models are lattice-gas models that are used for describing glassy systems. By construction, their equilibrium state is trivial and there are no equal-time correlations between the occupancy of different sites. We drive such models out of equilibrium by connecting them to two reservoirs of different densities, and we measure the response of the system to this perturbation. We find that under the proper coarse-graining, the behavior of these models may be expressed by a nonlinear diffusion equation, with a model- and density-dependent diffusion coefficient. We find a simple approximation for the diffusion coefficient, and we show that the relatively mild discrepancy between the approximation and our numerical results arises due to non-negligible correlations that appear as the system is driven out of equilibrium, even when the density gradient is infinitesimally small. Similar correlations appear when such kinetically constrained models are driven out of equilibrium by applying a uniform external force. We suggest that these correlations are the reason for the same discrepancy between the approximate diffusion coefficient and the numerical results for a broader group of models-nongradient lattice-gas models-for which kinetically constrained models are arguably the simplest example thereof.

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Section: A Kob-andersen Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrodynamics in kinetically constrained lattice-gas models

Teomy

Shokef

2017

Phys. Rev. E

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“…At low densities, they may also undergo gelation by increasing the mutual interactions among particles, prompting long-lived physical (reversible) bonding between particles, which thus facilitates the formation of percolated networks capable of sustaining weak mechanical stresses [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

“…Striking similarities, but also fundamental differences, have been highlighted between the microscopic dynamics and the mechanical response of both gels and glasses [30,31].…”

Section: Introductionmentioning

confidence: 99%

Arrested dynamics of the dipolar hard sphere model

et al. 2020

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We report the combined results of molecular dynamics simulations and theoretical calculations concerning various dynamical arrest transitions in a model system representing a dipolar fluid, namely, N (soft core) rigid spheres interacting through a truncated dipole-dipole potential. By exploring different regimes of concentration and temperature, we find three distinct scenarios for the slowing down of the dynamics of the translational and orientational degrees of freedom: At low (η = 0.2) and intermediate (η = 0.4) volume fractions, both dynamics are strongly coupled and become simultaneously arrested upon cooling. At high concentrations (η ≥ 0.6), the translational dynamics shows the features of an ordinary glass transition, either by compressing or cooling down the system, but with the orientations remaining ergodic, thus indicating the existence of partially arrested states. In this density regime, but at lower temperatures, the relaxation of the orientational dynamics also freezes. The physical scenario provided by the simulations is discussed and compared against results obtained with the self-consistent generalized Langevin equation theory, and both provide a consistent description of the dynamical arrest transitions in the system. Our results are summarized in an arrested states diagram which qualitatively organizes the simulation data and provides a generic picture of the glass transitions of a dipolar fluid. PACS numbers: xxxxxxxx yyyyyyyy

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“…To this aim it is useful to consider the presence of Dynamic Heterogeneities (DHs), groups of particles dynamically correlated over a time scale of the order of the relaxation time. In particular, the Dynamic Susceptibility χ 4 (k, t), commonly used to measure DHs, shows a different behaviour on approaching the two transitions [8]. For chemical gels, it was theoretically shown and numerically verified that at small wave vector (i.e.…”

Section: Introductionmentioning

confidence: 99%

Relaxation functions and dynamical heterogeneities in a model of chemical gel interfering with glass transition

Candia

Fierro

Pastore

et al. 2017

Eur. Phys. J. Spec. Top.

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Abstract. We investigate the heterogeneous dynamics in a model, where chemical gelation and glass transition interplay, focusing on the dynamical susceptibility. Two independent mechanisms give raise to the correlations, which are manifested in the dynamical susceptibility: one is related to the presence of permanent clusters, while the other is due to the increase of particle crowding as the glass transition is approached. The superposition of these two mechanisms originates a variety of different behaviours. We show that these two mechanisms can be unentangled considering the wave vector dependence of the dynamical susceptibility.

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Cluster structure and dynamics in gels and glasses

Cited by 4 publications

References 56 publications

Hydrodynamics in kinetically constrained lattice-gas models

Hydrodynamics in kinetically constrained lattice-gas models

Arrested dynamics of the dipolar hard sphere model

Relaxation functions and dynamical heterogeneities in a model of chemical gel interfering with glass transition

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