Departure coefficients, b, for levels of Fe I and Fe II as a function of log τ₅₀₀₀ in model atmosphere 4600/1.40/ − 2.60 from calculations using different treatment of H I collisions: pure electronic collisions (top panel); YBK18 + YBK19 (middle panel); B18 + YBK19 (bottom panel). Every fifth of the first 60 levels (E_exc ≤ 5.73 eV) of Fe I is shown. They are quoted in the bottom right part of each panel. All levels of Fe I above E_exc = 7 eV areplotted by black dotted curves. For Fe II, we show every fifth of the first 60 levels (E_exc ≤ 8.16 eV). They are quoted in the top right part of each panel. The letters z, y, x, … are used to denote the odd parity terms, and a, b, c, … for the even parity terms.