Top panel: comparison of the relative radiative acceleration in pure hydrogen atmospheres (solid curves) with our approximation given by Eq. (35) (dotted curves, which nearly coincide with solid curves) and with Paczynski’s approximation (34) (dashed curves). Bottom panel: comparison of the relative radiative acceleration for the fiducial model computed with different RFs: exact and approximate, angle-dependent, and angle-averaged. The relative radiative acceleration for Thomson scattering is also shown.