Kinetic Heterogeneities at Dynamical Crossovers

Abstract

We perform molecular dynamics simulations of a model glass-forming liquid to measure the size of kinetic heterogeneities, using a dynamic susceptibility ${\chi }_{\mathrm{ss}}(a,t)$ that quantifies the number of particles whose dynamics are correlated on the length scale $a$ and time scale $t$. By measuring ${\chi }_{\mathrm{ss}}(a,t)$ as a function of both $a$ and $t$, we locate local maxima ${\chi }^{\star }$ at distances $a^{\star }$ and times $t^{\star }$. Near the dynamical glass transition, we find two types of maxima, both correlated with crossovers in the dynamical behavior: a smaller maximum corresponding to the crossover from ballistic to sub-diffusive motion, and a larger maximum corresponding to the crossover from sub-diffusive to diffusive motion. Our results indicate that kinetic heterogeneities are not necessarily signatures of an impending glass or jamming transition.

6 pages, 4 figures

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Cited by in corpus (5)

• Short-time $\beta$-relaxation in glass-forming liquids is cooperative in nature
• Intermediate regimes in granular Brownian motion: Superdiffusion and subdiffusion
• Dynamical heterogeneity in soft particle suspensions under shear
• Jamming transition of kinetically-constrained models in rectangular systems
• Jamming by Shape in Kinetically-Constrained Models