Synthesis of Fe lines used in this work. In each sub-panel the upper part shows the 1D–LTE synthesis (dashed black line), the 3D–LTE synthesis (green), and for some sub-panels the 1D–NLTE synthesis from Kovalev et al. (2018; blue) for a T_eff = 4500 K, log g = 2.5, [M/H] = −1.0 model. The lower parts display the corresponding differences in abundances of the same line between the 1D–LTE model and the 3D model for various temperatures and metallicities (large symbols T_eff = 4000 K, log g = 1.5; medium-sizesymbols T_eff = 4500 K, log g = 2.5; small symbols T_eff = 5000 K, log g = 2.5).