α-relaxation processes in binary hard-sphere mixtures

Foffi, Giuseppe; Götze, W.; Sciortino, Francesco; Tartaglia, P.; Voigtmann, Thomas

doi:10.1103/physreve.69.011505

Cited by 100 publications

(163 citation statements)

References 32 publications

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“…True multi-species MCT calculations like in Ref. [46] would be required to capture all polydispersity aspects, yet are too demanding in the present case. All elements of the matrix of partial structure factors would be required, and the multiple wavevector integrations over the required large q-ranges would crucially slow down the MCT numerics.…”

Section: Resultsmentioning

confidence: 99%

Bond formation and slow heterogeneous dynamics in adhesive spheres with long-ranged repulsion: Quantitative test of mode coupling theory

et al. 2007

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A colloidal system of spheres interacting with both a deep and narrow attractive potential and a shallow long-ranged barrier exhibits a prepeak in the static structure factor. This peak can be related to an additional mesoscopic length scale of clusters and/or voids in the system. Simulation studies of this system have revealed that it vitrifies upon increasing the attraction into a gel-like solid at intermediate densities. The dynamics at the mesoscopic length scale corresponding to the prepeak represents the slowest mode in the system. Using mode coupling theory with all input directly taken from simulations, we reveal the mechanism for glassy arrest in the system at 40% packing fraction. The effects of the low-q peak and of polydispersity are considered in detail. We demonstrate that the local formation of physical bonds is the process whose slowing down causes arrest. It remains largely unaffected by the large-scale heterogeneities, and sets the clock for the slow cluster mode. Results from mode-coupling theory without adjustable parameters agree semi-quantitatively with the local density correlators but overestimate the lifetime of the mesoscopic structure (voids).

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Section: Resultsmentioning

confidence: 99%

Bond formation and slow heterogeneous dynamics in adhesive spheres with long-ranged repulsion: Quantitative test of mode coupling theory

et al. 2007

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“…Despite their simplicity, hard-sphere systems are well characterized, experimentally realizable, and show all of the features of glassy behaviour that are exhibited by more complex fluids. It is well known from experiment and simulation that classical hard spheres enter a glassy regime for volume fractions in the range φ = 50-60% independent of temperature 18,19 . Figure 1 shows the full structure of the dynamical phase diagram.…”

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confidence: 99%

Quantum fluctuations can promote or inhibit glass formation

et al. 2011

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Glasses are dynamically arrested states of matter that do not exhibit the long-range periodic structure of crystals 1-4 . Here we develop new insights from theory and simulation into the impact of quantum fluctuations on glass formation. As intuition may suggest, we observe that large quantum fluctuations serve to inhibit glass formation as tunnelling and zero-point energy allow particles to traverse barriers facilitating movement. However, as the classical limit is approached a regime is observed in which quantum effects slow down relaxation making the quantum system more glassy than the classical system. This dynamical 'reentrance' occurs in the absence of obvious structural changes and has no counterpart in the phenomenology of classical glass-forming systems.Although a wide variety of glassy systems ranging from metallic to colloidal can be accurately described using classical theory, quantum systems ranging from molecular, to electronic and magnetic form glassy states 5,6 . Perhaps the most intriguing of these is the coexistence of superfluidity and dynamical arrest, namely the 'superglass' state suggested by recent numerical, theoretical and experimental work [7][8][9] . Although such intriguing examples exist, at present there is no unifying framework to treat the interplay between quantum and glassy fluctuations in the liquid state.To attempt to formulate a theory for a quantum liquid to glass transition, we may first appeal to the classical case for guidance. Here, a microscopic theory exists in the form of mode-coupling theory (MCT), which requires only simple static structural information as input and produces a full range of dynamical predictions for time correlation functions associated with single-particle and collective fluctuations 10 . Although MCT has a propensity to overestimate a liquid's tendency to form a glass, it has been shown to account for the emergence of the non-trivial growing dynamical length scales associated with vitrification 11 . Perhaps more importantly, MCT has made numerous non-trivial predictions ranging from logarithmic temporal decay of density fluctuations and reentrant dynamics in adhesive colloidal systems to various predictions concerning the effect of compositional mixing on glassy behaviour 12,13 . These have been confirmed by both simulation and experiment [14][15][16] .A fully microscopic quantum version of MCT (QMCT) that requires only the observable static structure factor as input may be developed along the same lines as the classical version. Indeed, a zero-temperature version of such a theory has been developed and successfully describes the wave-vector-dependent dispersion in superfluid helium 17 . In the Supplementary Information, we outline the derivation of a full temperature-dependent QMCT. In the limit of high temperatures, our theory reduces to the hard-sphere fluid. φ is the volume fraction, Λ * = (βh 2 /mσ 2 ) 1/2 is the thermal wavelength in units of inter-particle separation σ , and β = 1/k B T is the inverse temperature. The approach by which the...

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“…Understanding the global patterns from the mobility of individual constituents are difficult to monitor experimentally [24]. However, it is relatively easier to investigate flow and patterns [25,26] in such a complex particulate mixture by computer simulation methods such as lattice gas [27,28], molecular dynamics [29,30], and Monte Carlo [31] methods. Most of the particulate driven system [13][14][15][16][17][18][19][20][21][22][23] deal with conservative systems with a constant number of constituents.…”

Section: Physica a 358 (2005) 437-446mentioning

confidence: 99%