Relationships between Self-Diffusivity, Packing Fraction, and Excess Entropy in Simple Bulk and Confined Fluids

@article{citeulike:1838161, abstract = {Abstract: Static measures such as density and entropy, which are intimately connected to structure, have featured prominently in modern thinking about the dynamics of the liquid state. Here, we explore the connections between self-diffusivity, density, and excess entropy for two of the most widely used model "simple" liquids, the equilibrium Lennard-Jones and square-well fluids, in both bulk and confined environments. We find that the self-diffusivity data of the Lennard-Jones fluid can be approximately collapsed onto a single curve (i) versus effective packing fraction and (ii) in appropriately reduced form versus excess entropy, as suggested by two well-known scaling laws. Similar data collapse does not occur for the square-well fluid, a fact that can be understood on the basis of the nontrivial effects that temperature has on its static structure. Nonetheless, we show that the implications of confinement for the self-diffusivity of both of these model fluids, over a broad range of equilibrium conditions, can be predicted on the basis of knowledge of the bulk fluid behavior and either the effective packing fraction or the excess entropy of the confined fluid. Excess entropy is perhaps the most preferable route due to its superior predictive ability and because it is a standard, unambiguous thermodynamic quantity that can be readily predicted via classical density functional theories of inhomogeneous fluids.}, address = {Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas, Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York, and Institute for Theoretical Chemistry, The University of Texas at Austin, Austin, Texas}, author = {Mittal, J. and Errington, J. R. and Truskett, T. M. }, citeulike-article-id = {1838161}, doi = {http://dx.doi.org/10.1021/jp071369e}, journal = {J. Phys. Chem. B}, keywords = {2007, confinement, fluid}, month = {August}, number = {34}, pages = {10054--10063}, posted-at = {2008-04-29 01:00:48}, priority = {2}, title = {Relationships between Self-Diffusivity, Packing Fraction, and Excess Entropy in Simple Bulk and Confined Fluids}, url = {http://dx.doi.org/10.1021/jp071369e}, volume = {111}, year = {2007} }

TY - JOUR ID - citeulike:1838161 L3 - citeulike-article-id:1838161 TI - Relationships between Self-Diffusivity, Packing Fraction, and Excess Entropy in Simple Bulk and Confined Fluids JF - J. Phys. Chem. B VL - 111 IS - 34 SP - 10054 EP - 10063 AD - Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas, Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York, and Institute for Theoretical Chemistry, The University of Texas at Austin, Austin, Texas N2 - Abstract: Static measures such as density and entropy, which are intimately connected to structure, have featured prominently in modern thinking about the dynamics of the liquid state. Here, we explore the connections between self-diffusivity, density, and excess entropy for two of the most widely used model "simple" liquids, the equilibrium Lennard-Jones and square-well fluids, in both bulk and confined environments. We find that the self-diffusivity data of the Lennard-Jones fluid can be approximately collapsed onto a single curve (i) versus effective packing fraction and (ii) in appropriately reduced form versus excess entropy, as suggested by two well-known scaling laws. Similar data collapse does not occur for the square-well fluid, a fact that can be understood on the basis of the nontrivial effects that temperature has on its static structure. Nonetheless, we show that the implications of confinement for the self-diffusivity of both of these model fluids, over a broad range of equilibrium conditions, can be predicted on the basis of knowledge of the bulk fluid behavior and either the effective packing fraction or the excess entropy of the confined fluid. Excess entropy is perhaps the most preferable route due to its superior predictive ability and because it is a standard, unambiguous thermodynamic quantity that can be readily predicted via classical density functional theories of inhomogeneous fluids. KW - 2007 KW - confinement KW - fluid AU - Mittal, J AU - Errington, JR AU - Truskett, TM PY - 2007/08/30/ UR - http://dx.doi.org/10.1021/jp071369e ER -