With the trained ReaxFF force field, the hcp sites are stable but, similar to fcc sites, the In the DFT reference data, the site further away from the surface is more stable (-4.05 eV vs. -3.92 eV). In summary, DFT calculations suggest that on Mg(0001), the adsorption sites in between the first and second surface layers are the most stable. With the trained force field, diffusion to deeper layers is calculated to be more favorable from a thermodynamic point of view.