Comparison of Hα line profiles predicted by fastwind (red) and WM-basic (black). To focus the comparison on the NLTE modeling and the treatment of radiative transfer, these WM-basic calculations use the density structures from the fastwind models. Top row: T_eff = 50 000 K test model (S50), bottom row: T_eff = 35 000 K test model (S35). Left panels: profiles from a smooth, unclumped flow (f_cl = 1), right panels: profiles from a clumped flow (f_cl = 81) with a correspondingly reduced mass loss rate (by a factor of ). The differences between our WM-basic predictions and those from fastwind are negligible compared to the sensitive dependence of the Hα line on the clumping factor, as illustrated by Fig. 5.