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Confinement, Entropy, and Single-Particle Dynamics of Equilibrium Hard-Sphere Mixtures



Jeetain Mittal, Vincent K. Shen, Jeffrey R. Errington, Thomas M. Truskett


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.
Journal of Chemical Physics


diffusivity, entropy, fluid mixtures, hard spheres, molecular dynamics, Monte Carlo, thermodynamics


Mittal, J. , Shen, V. , Errington, J. and Truskett, T. (2007), Confinement, Entropy, and Single-Particle Dynamics of Equilibrium Hard-Sphere Mixtures, Journal of Chemical Physics (Accessed April 24, 2024)
Created October 17, 2007, Updated October 12, 2021