title: Thermodynamic scaling and corresponding states for the self-diffusion coefficient of non-conformal soft-sphere fluids.
abstract: In this work, we explore transport properties of a special type of repulsive spheres that exhibit remarkable scaling of their thermodynamic properties. In order to accomplish that we propose a new way to derive and express effective hard-sphere diameters for transport properties of simple fluids. The procedure relies on mapping the system's transport properties, in the low density limit, to the hard-sphere fluid. We have chosen a set of soft-sphere systems characterised by a well-defined variation of their softness. These systems represent an extension of the repulsive Lennard-Jones potential widely used in statistical mechanics of fluids and are an accurate representation of the effective repulsive potentials of real systems. The self-diffusion coefficient of the soft-sphere fluids is obtained by equilibrium molecular dynamics. The soft-sphere collision integrals of different systems are shown to follow quite simple relationships between each other. These collision integrals are incorporated, through the definition of the effective hard-sphere diameter, in the resulting equation for the self-diffusion coefficient. The approach followed exhibits a density rescaling that leads to a single master curve for all systems and temperatures. The scaling is carried through to the level of the mean-squared displacement.
authors.affiliation: Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Apdo 55 534, México DF 09340, México. xclassicx@gmail.com
authors.forename: Tonalli
authors.initials: T
authors.lastname: Rodríguez-López
authors.forename: J Antonio
authors.initials: JA
authors.lastname: Moreno-Razo
authors.forename: Fernando
authors.initials: F
authors.lastname: del Río