title: Structure, thermodynamics, and position-dependent diffusivity in fluids with sinusoidal density variations.
abstract: Molecular dynamics simulations and a stochastic method based on the Fokker-Planck equation are used to explore the consequences of inhomogeneous density profiles on the thermodynamic and dynamic properties of the hard-sphere fluid and supercooled liquid water. Effects of the inhomogeneity length scale are systematically considered via the imposition of sinusoidal density profiles of various wavelengths. For long-wavelength density profiles, bulk-like relationships between local structure, thermodynamics, and diffusivity are observed as expected. However, for both systems, a crossover in behavior occurs as a function of wavelength, with qualitatively different correlations between the local static and dynamic quantities emerging as density variations approach the scale of a particle diameter. Irrespective of the density variation wavelength, average diffusivities of hard-sphere fluids in the inhomogeneous and homogeneous directions are coupled and approximately correlate with the volume available for insertion of another particle. Unfortunately, a quantitatively reliable static predictor of position-dependent dynamics has yet to be identified for even the simplest of inhomogeneous fluids.
authors.affiliation: McKetta Department of Chemical Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Bollinger
authors.forename: Avni
authors.initials: A
authors.lastname: Jain
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Truskett