Emergent spectra (top panel) and temperature structures (bottom panel) for the fiducial model atmosphere (solid curve) and for model atmospheres that are calculated using the fixed-ions approximation for the reflectivity calculations (dashed curves), and the inner boundary condition from Paper II (dotted curves). In the top panel the diluted blackbody spectrum that fits the high-energy part of the fiducial model spectrum is also shown (dash-dotted curve).