Results for the inversion of the Fe I 15 648 Å synthetic profile presented in Fig. 11 in black (top row). This profile was synthesised considering collisions with H. The effects of fitting this profile taking into account collisions with neutral hydrogen are plotted in blue, and those without considering collisions are shown in red. Bottom row: atmosphere that produced the input profiles (black) and the atmosphere inferred considering collisions with H (blue) and considering no collisions (red). We show the differences between the two studies at the bottom of the four Stokes parameters and the temperature panels.