A quasi-universal scaling law for atomic transport in simple fluids

A semi-empirical 'universal' corresponding-states relationship, for the dim ensionless transport coefficients of dense fluids as functions of the reduc ed configurational entropy, was proposed more than twenty years ago and est ablished by many simulations. Here it is shown analytically, by appealing t o Enskog's original results for the inverse-power potentials, that the quas i-universal entropy scaling can be extended also to dilute gases. The analy tic form and the possible origin for the entropy scaling for dense fluids a re discussed in view of this unexpected result. On the basis of the entropy scaling we predict a minimum in the shear viscosity as a function of tempe rature for all soft inverse-power potentials, in quantitative agreement wit h the available simulations.