Suppression of the rate of growth of dynamic heterogeneities and its relation to the local structure in a supercooled polydisperse liquid

Abraham, Sneha Elizabeth; Bagchi, Biman

doi:10.1103/physreve.78.051501

Cited by 15 publications

(13 citation statements)

References 37 publications

(33 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the dynamics of the strong liquid can be interpreted as mostly occurring through the rearrangement of strongly connecting tetrahedral networks. Interestingly, a similar suppression of χ 4 (k, t) in strong liquids, for longer times, has been observed in polydispersed systems 73,176 , colloidal gels 177,178 , and confined systems in random media 179,180 .…”

Section: B Four-point Correlations and The Growing Length Scale Of Dsupporting

confidence: 67%

Multiple length and time scales of dynamic heterogeneities in model glass-forming liquids: A systematic analysis of multi-point and multi-time correlations

Kim

Saito

2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

We report an extensive and systematic investigation of the multi-point and multi-time correlation functions to reveal the spatio-temporal structures of dynamic heterogeneities in glass-forming liquids. Molecular dynamics simulations are carried out for the supercooled states of various prototype models of glass-forming liquids such as binary Kob-Andersen, Wahnström, soft-sphere, and network-forming liquids. While the first three models act as fragile liquids exhibiting superArrhenius temperature dependence in their relaxation times, the last is a strong glass-former exhibiting Arrhenius behavior. First, we quantify the length scale of the dynamic heterogeneities utilizing the four-point correlation function. The growth of the dynamic length scale with decreasing temperature is characterized by various scaling relations that are analogous to the critical phenomena. We also examine how the growth of the length scale depends upon the model employed. Second, the four-point correlation function is extended to a three-time correlation function to characterize the temporal structures of the dynamic heterogeneities based on our previous studies [K. Kim and S. Saito, Phys. Rev. E 79, 060501(R) (2009); J. Chem. Phys. 133, 044511 (2010)]. We provide comprehensive numerical results obtained from the three-time correlation function for the above models. From these calculations, we examine the time scale of the dynamic heterogeneities and determine the associated lifetime in a consistent and systematic way. Our results indicate that the lifetime of the dynamical heterogeneities becomes much longer than the α-relaxation time determined from a two-point correlation function in fragile liquids. The decoupling between the two time scales is remarkable, particularly in supercooled states, and the time scales differ by more than an order of magnitude in a more fragile liquid. In contrast, the lifetime is shorter than the α-relaxation time in tetrahedral network-forming strong liquid, even at lower temperatures.

show abstract

Section: B Four-point Correlations and The Growing Length Scale Of Dsupporting

confidence: 67%

Multiple length and time scales of dynamic heterogeneities in model glass-forming liquids: A systematic analysis of multi-point and multi-time correlations

Kim

Saito

2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Neighborhood definitions based on cutoff radii are widely used, e.g., with cutoff radii 1.2σ and 1.4σ 11,18,24,37,47 or with the value of the cutoff radius determined by the first minimum of the two-point correlation function g(r). 9,14,15,25,48 Alternatively, the Delaunay graph of the particle centers 49,50 is used to define NN. 5,20,23,41,51 In this parameterfree method, every sphere which is connected to a sphere a by a Delaunay edge is considered a NN of a.…”

Section: Ambiguity Of the Neighborhood Definition And Its Effect On Q Lmentioning

confidence: 99%

“…4,8,11,[20][21][22] While q l is defined as a local parameter for each particle, other studies have used global averages of bond angles (Q l ) to detect single-crystalline order across the entire sample. [23][24][25] The BOO parameters q l and Q l are defined as structure metrics for ensembles of N spherical particles. For a given sphere a, one assigns a set of nearest neighbors (NN) spheres NN(a).…”

mentioning

confidence: 99%

Shortcomings of the bond orientational order parameters for the analysis of disordered particulate matter

Mickel¹,

Kapfer²,

Schröder‐Turk³

et al. 2013

The Journal of Chemical Physics

251

236

View full text Add to dashboard Cite

Local structure characterization with the bond-orientational order parameters q 4 , q 6 ,. . . introduced by Steinhardt et al. has become a standard tool in condensed matter physics, with applications including glass, jamming, melting or crystallization transitions and cluster formation. Here we discuss two fundamental flaws in the definition of these parameters that significantly affect their interpretation for studies of disordered systems, and offer a remedy. First, the definition of the bond-orientational order parameters considers the geometrical arrangement of a set of neighboring spheres NN(p) around a given central particle p; we show that procedure to select the spheres constituting the neighborhood NN(p) can have greater influence on both the numerical values and qualitative trend of q l than a change of the physical parameters, such as packing fraction. Second, the discrete nature of neighborhood implies that NN(p) is not a continuous function of the particle coordinates; this discontinuity, inherited by q l , leads to a lack of robustness of the q l as structure metrics. Both issues can be avoided by a morphometric approach leading to the robust Minkowski structure metrics q ′ l . These q ′ l are of a similar mathematical form as the conventional bond-orientational order parameters and are mathematically equivalent to the recently introduced Minkowski tensors [Europhys. Lett. 90, 34001 (2010); Phys. Rev. E. 85, 030301 (2012)].

show abstract

“…The participation ratio of the modes decreases with polydispersity for modes of all frequencies(See FIGURE 7) implying that the number of particles participating in a mode of given frequency decreases with S. Thus the vibrations become more localized with S. This means that as size disparity among the particles increases, the system cannot sustain propagating modes. It is interesting to note here that the large size disparity among the particles also leads to the suppression of growth of dynamic heterogeneity with polydispersity in supercooled liquids(See [23]). Dynamic heterogeneity in supercooled liquids in its simplest sense means clusters of fast-moving particles that move together for a certain amount of time before they get decorrelated.…”

Section: A Polydispersity Effects On Vibrational Density Of Statesmentioning

confidence: 94%

“…In this study we investigate the vibrational dynamics and boson peak in a polydisperse Lennard-Jones liquid. Polydisperse liquid is one of the simplest model systems that exhibit glass transition and can be conveniently studied via both experiments [19,20] and computer simulations as the size distribution of particles prevents crystallization [21,22,23]. The rest of the paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Vibrational dynamics and boson peak in a supercooled polydisperse liquid

Abraham

Bagchi

2010

Phys. Rev. E

Self Cite

View full text Add to dashboard Cite

Vibrational density of states (VDOS) in a supercooled polydisperse liquid is computed by diagonalizing the Hessian matrix evaluated at the potential energy minima for systems with different values of polydispersity. An increase in polydispersity leads to an increase in the relative population of localized high-frequency modes. At low frequencies, the density of states shows an excess compared to the Debye squared-frequency law, which has been identified with the boson peak. The height of the boson peak increases with polydispersity and shows a rather narrow sensitivity to changes in temperature. While the modes comprising the boson peak appear to be largely delocalized, there is a sharp drop in the participation ratio of the modes that exist just below the boson peak indicative of the quasilocalized nature of the low-frequency vibrations. Study of the difference spectrum at two different polydispersity reveals that the increase in the height of boson peak is due to a population shift from modes with frequencies above the maximum in the VDOS to that below the maximum, indicating an increase in the fraction of the unstable modes in the system. The latter is further supported by the facilitation of the observed dynamics by polydispersity. Since the strength of the liquid increases with polydispersity, the present result provides an evidence that the intensity of boson peak correlates positively with the strength of the liquid, as observed earlier in many experimental systems.

show abstract

Suppression of the rate of growth of dynamic heterogeneities and its relation to the local structure in a supercooled polydisperse liquid

Cited by 15 publications

References 37 publications

Multiple length and time scales of dynamic heterogeneities in model glass-forming liquids: A systematic analysis of multi-point and multi-time correlations

Multiple length and time scales of dynamic heterogeneities in model glass-forming liquids: A systematic analysis of multi-point and multi-time correlations

Shortcomings of the bond orientational order parameters for the analysis of disordered particulate matter

Vibrational dynamics and boson peak in a supercooled polydisperse liquid

Contact Info

Product

Resources

About