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GR-reduced long-time diffusivity, (1 − D/D 0) GR , vs negative excess entropy −s ex /k B for (a) IPL, (b) Hertzian and (c) Gaussian-core fluids. The IPL fluids have exponents μ discussed in the text. The solid black curve is a least-squares fit to the IPL data from (a). The dashed red lines indicate a difference of 20% from the IPL fit. The insets show the reduced diffusivity change, 1 − D/D 0, as a function of density, ρσ3.
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GR predictions (curves, discussed in text) and Brownian dynamics simulation data (symbols) for long-time diffusivity of the (a)Hertzian and (b) Gaussian-core fluids as a function of density ρσ3.
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Computer simulations are used to test whether a recently introduced generalization of Rosenfeld's excess-entropy scaling method for estimating transport coefficients in systems obeying molecular dynamics can be extended to predict long-time diffusivities in fluids of particles undergoing Brownian dynamics in the absence of interparticle hydrodynamic forces. Model fluids with inverse-power-law, Gaussian-core, and Hertzian pair interactions are considered. Within the generalized Rosenfeld scaling method, long-time diffusivities of ultrasoft Gaussian-core and Hertzian particle fluids, which display anomalous trends with increasing density, are predicted (to within 20%) based on knowledge of interparticle interactions, excess entropy, and scaling behavior of simpler inverse-power-law fluids.
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