Rosseland-mean opacities, κ_R [cm² g^-1], vs. lgT for LTE (dotted lines) and non-LTE (dashed lines) models calculated with the TLUSTY200 computing code for T_eff = 25   000 K and lgg = 4.0 with different mixtures of elements compared with the ATLAS12/MHD-Q models (thick lines). The chemical compositions of elements are the following: H+He (panels a) and b)), H–Ca (panels c) and d)), H+He+Fe (panels e) and f)) and all elements considered in the codes (panels g) and h)). The right-hand side panels display the same models as the left-hand side ones, but only the outermost layers are shown.