Transport coefficients of soft sphere fluids at high densities

TL;DR

This study uses molecular dynamics simulations to analyze the transport properties of soft-sphere fluids at high densities, focusing on diffusion and viscosity along the melting line, and tests various scaling relations.

Contribution

It provides new insights into the behavior of soft-sphere fluids at high densities, including validation of the Stokes-Einstein relation and viscosity trends along the melting line.

Findings

The Stokes-Einstein relation holds when using Barker diameter.

Viscosity exhibits non-monotonic behavior along isochores.

Viscosity increases significantly along the melting line without inducing glass transition.

Abstract

Molecular dynamics computer simulation has been used to compute the self-diffusion coefficient, and shear viscosity of soft-sphere fluids, in which the particles interact through the soft-sphere or inverse power pair potential. The calculations have been made along the melting line in a wide range of pressures and temperatures. The validity of scaling relations for thermodynamic parameters and kinetic coefficients was checked. It was shown that the Stokes-Einstein relationship is obeyed if the Barker diameter is used as a characteristic length scale. It was also shown that the viscosity is non-monotonic along the isochores as predicted by Ya. Rosenfeld. It was shown that the viscosity is strongly growing along the melting line, however, this increase does not stimulate the glass transition because the relaxation time is decreasing.