  Here, we compare radiative accelerations (g_rad) derived from the new Opacity
Project (OP) data with those computed from OPAL and some previous data from OP.
For the case where we have full data from OPAL, the differences in the
Rosseland mean opacities between OPAL and the new OP data are within 12% and
less than 30% between new OP and previous OP data (OP1 at CDS). The radiative
accelerations g_rad differ at up to the 17% level when compared to OPAL and up
to the 38% level when compared to OP1. The comparison with OP1 on a larger
(rho-T) space gives a difference of up to 40% for g_rad(C). And it increases
for heavier elements. The differences increase for heavier elements reaching
60% for Si and 65% for S and Fe. We also constructed four representative
stellar models in order to compare the new OP accelerations with prior
published results that used OPAL data. The Rosseland means overall agree better
than 10% for all of our cases. For the accelerations, the comparisons with
published values yield larger differences in general. The published OPAL
accelerations for carbon are even larger relative to OP compare to what our
direct comparisons would indicate. Potential reasons for this puzzling behavior
are discussed. In light of the significant differences in the inferred
acceleration rates, theoretical errors should be taken into account when
comparing models with observations. The implications for stellar evolution are
briefly discussed. The sensitivity of g_rad to the atomic physics may provide a
useful test of different opacity sources.
