The Stokes–Einstein
(SE) equation is often applied as an
approximation of self-diffusion coefficients D of
molecular species based on the shear viscosity of fluids. The SE relation
gives rough estimates of self-diffusion coefficients in liquid states
and (divergently) high deviations for the gaseous phase. Inspired
by Rosenfeld’s entropy scaling approach, we find a universal
function of residual entropy f(s
res) to describe the ratio between experimental and calculated D from SE equation for all investigated substances. The
so-obtained modified SE equation, containing 5 universal parameters
adjusted to experimental data of 61 substances of 11 different chemical
families, can be used for predicting D in the entire
fluid region, with averaged absolute deviations of 12.3% compared
to experimental data (5407 data points). The application of the proposed
model to diffusion coefficients at infinite dilution shows average
deviations of 20.8% for widely different systems (412 data points).
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