Cofinement, entropy, and single-particle dynamics of equilibrium hard-sphere mixtures

Abstract

We use discontinuous molecular dynamics and grand-canonical transition-matrix Monte Carlo simulations to explore how confinement between parallel hard walls modifies the relationships between packing fraction, self-diffusivity, partial molar excess entropy, and total excess entropy for binary hard-sphere mixtures. To accomplish this, we introduce an efficient algorithm to calculate partial molar excess entropies from the transition-matrix Monte Carlo simulation data. We find that the species-dependent self-diffusivities of confined fluids are very similar to those of the bulk mixture if compared at the same, appropriately defined, packing fraction up to intermediate values, but then deviate negatively from the bulk behavior at higher packing fractions. On the other hand, the relationships between self-diffusivity and partial molar excess entropy (or total excess entropy) observed in the bulk fluid are preserved under confinement even at relatively high packing fractions and for different mixture compositions. This suggests that the partial molar excess entropy, calculable from classical density functional theories of inhomogeneous fluids, can be used to predict some of the nontrivial dynamical behaviors of fluid mixtures in confined environments.

submitted to JCP

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• Non-monotonic effect of confinement on the glass transition
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• Enhancing tracer diffusivity by tuning interparticle interactions and coordination shell structure
• Local structure-mobility relationships of confined fluids reverse upon supercooling
• Entropy Scaling for Diffusion Coefficients in Fluid Mixtures
• Dynamical properties of densely packed confined hard-sphere fluids
• Dynamic properties of quasi-confined colloidal hard-sphere liquids near the glass transition
• Tuning structure and mobility of solvation shells surrounding tracer additives
• Computer Simulations and Mode-Coupling Theory of Glass-Forming Confined Hard-Sphere Fluids
• Tagged-particle dynamics in confined colloidal liquids