How short-range attractions impact the structural order, self-diffusivity, and viscosity of a fluid

Abstract

We present molecular simulation data for viscosity, self-diffusivity, and the local structural ordering of (i) a hard-sphere fluid and (ii) a square-well fluid with short-range attractions. The latter fluid exhibits a region of dynamic anomalies in its phase diagram, where its mobility increases upon isochoric cooling, which is found to be a subset of a larger region of structural anomalies, in which its pair correlations strengthen upon isochoric heating. This "cascade of anomalies" qualitatively resembles that found in recent simulations of liquid water. The results for the hard-sphere and square-well systems also show that the breakdown of the Stokes-Einstein relation upon supercooling occurs for conditions where viscosity and self-diffusivity develop different couplings to the degree of pairwise structural ordering of the liquid. We discuss how these couplings reflect dynamic heterogeneities. Finally, we note that the simulation data suggests how repulsive and attractive glasses may generally be characterized by two distinct levels of short-range structural order.

9 pages, 9 figures Submitted to The Journal of Chemical Physics

References in corpus (16)

• Higher order glass-transition singularities in colloidal systems with attractive interactions
• Nonergodicity transitions in colloidal suspensions with attractive interactions
• Reentrant glass transition in a colloid-polymer mixture with depletion attractions
• Heterogeneous Diffusion in Highly Supercooled Liquids
• Ideal glass-glass transitions and logarithmic decay of correlations in a simple system
• Molecular structural order and anomalies in liquid silica
• Comparative simulation study of colloidal gels and glasses
• Excess entropy, Diffusivity and Structural Order in liquids with water-like anomalies
• Nature of the Breakdown in the Stokes-Einstein Relationship in a Hard Sphere Fluid
• Thermodynamic and dynamic anomalies for a three dimensional isotropic core-softened potential
• Confirmation of Anomalous Dynamical Arrest in attractive colloids: a molecular dynamics study
• Simulation study of Non-ergodicity Transitions: Gelation in Colloidal Systems with Short Range Attractions
• Dynamical heterogeneities close to a colloidal gel
• A Family of Tunable Spherically-Symmetric Potentials that Span the Range from Hard Spheres to Water-like Behavior
• Evidence for Unusual Dynamical Arrest Scenario in Short Ranged Colloidal Systems
• Model for the free-volume distributions of equilibrium fluids

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