Take a sneak peek at the new NIST.gov and let us know what you think!
(Please note: some content may not be complete on the beta site.).

View the beta site
NIST logo

Publication Citation: Composition and concentration anomalies for structure and dynamics of Gaussian-core mixtures

NIST Authors in Bold

Author(s): Vincent K. Shen; Mark J. Pond; William P. Krekelberg; Jeffrey R. Errington; Thomas M. Truskett;
Title: Composition and concentration anomalies for structure and dynamics of Gaussian-core mixtures
Published: August 25, 2009
Abstract: We report molecular dynamics simulation results for two-component fluid mixtures of Gaussian-core particles, focusing on how tracer diffusivities and static pair correlations depend on temperature, particle concentration, and composition. At low particle concentrations, these systems behave like simple atomic mixtures. However, for intermediate concentrations, the single-particle dynamics of the two species largely decouple, giving rise to the following anomalous trends. Increasing either the concentration of the fluid (at fixed composition) or the mole fraction of the larger particles (at fixed particle concentration) enhances the tracer diffusivity of the larger particles, but decreases that of the smaller particles. In fact, at sufficiently high particle concentrations, the larger particles exhibit higher mobility than the smaller particles. Each of these dynamic behaviors is accompanied by a corresponding structural trend that characterizes how either concentration or composition affects the strength of the static pair correlations. Specifically, the dynamic trends observed here are consistent with a single empirical scaling law that relates an appropriately normalized tracer diffusivity to its pair-correlation contribution to the excess entropy.
Citation: Journal of Chemical Physics
Keywords: Gaussian-core fluid, simulation, statistical mechanics
Research Areas: Physical Properties, Molecular Dynamics, Thermodynamics, Thermophysics