Fig. 1: Equation of state of pure liquid Fe and Fe-Mg alloys under Earth’s outer conditions.

Seven supercells, Fe80 (black), Fe78Mg1 (red), Fe78Mg2 (blue), Fe78Mg3 (yellow), Fe78Mg4 (cyan), Fe78Mg6 (magenta), and Fe78Mg8 (green), were investigated. The equations of state are plotted along different isotherms of 6000 K (a), 6500 K (b), 7000 K (c), and 7500 K (d). The fitting parameters are listed in Supplementary Table S1.