  Self- and binary Maxwell-Stefan diffusion coefficients were determined by
equilibrium molecular dynamics simulations with the Green-Kubo method. This
study covers self-diffusion coefficients at liquid states for eight pure
fluids, i.e. F$_2$, N$_2$, CO$_2$, CS$_2$, C$_2$H$_6$, C$_2$H$_4$, C$_2$H$_2$
and SF$_6$ as well as Maxwell-Stefan diffusion coefficients for three binary
mixtures N$_2$+CO$_2$, N$_2$+C$_2$H$_6$ and CO$_2$+C$_2$H$_6$. The fluids were
modeled by the two-center Lennard-Jones plus point-quadrupole pair potential,
with parameters taken from previous work of our group which were determined
solely on the basis of vapor-liquid equilibrium data. Self-diffusion
coefficients are predicted with a statistical uncertainty less than 1% and they
agree within 2% to 28% with the experimental data. The correction of the
simulation data due to the finite size of the system increases the value of the
self-diffusion coefficient typically by 10%. If this correction is considered,
better agreement with the experimental data can be expected for most of the
studied fluids. Maxwell-Stefan diffusion coefficients for three binary mixtures
were also predicted, their statistical uncertainty is about 10%. These results
were used to test three empirical equations to estimate Maxwell-Stefan
diffusion coefficients in binary mixtures, i.e. the equations of Caldwell and
Babb, of Darken, and of Vignes. The equations of Caldwell and Babb and of
Vignes show qualitatively different behavior of the Maxwell-Stefan diffusion
coefficient than that observed in the simulations. In agreement with previous
work, the best results are obtained in all cases with the equation of Darken.
