Iteration behavior of the maximum absolute relative changes in atomic level population max | δn/n | (left) and in angle-averaged intensity max | δJ/J | (right) in the 3D Bifrost model atmosphere for the six-level hydrogen model atom with the Ly α line treated in PRD. The top row shows the behavior with two subiterations, the bottom row with three subiterations. We note that the max | δn/n | values for the excited states of H i and the H ii continuum overlap.