The first oxygen molecules hitting the metal surface instantaneously dissociate and heat the surface to several 1000 K within the first 0.1 ns. On Mg(0001), the high temperature causes short-term detachment of individual MgO clusters, which later readsorb on the surface. In addition, the elevated temperature causes high mobility at the interface, leading to surface recrystallization into the rocksalt structure. However, the structures observed in this simulation are significantly more disordered compared to the recrystallized MgO particle (Fig. ), showing a multitude of grain boundaries connecting several rocksalt phase domains.