However, sub-nano clusters usually sinter by means of Ostwald ripening, where a single atom is detached from the cluster, migrates through the surface or forming gaseous species, and re-attaches to a larger particle. Thus, the energy required for one Pt (or Ge) atom to be detached from the cluster and placed on the preferred site on the support is computed. A larger positive dissociation energy indicates that the cluster needs more energy to lose one Pt (Ge) atom, and thus, it is more stable and less likely to break apart. The addition of Ge systematically makes it more difficult for a Pt atom to detach from the cluster. Contrary to what is observed for the E ads , the greater stability is found in Pt 4 Ge 4 . This agrees with the fact that clusters always use Pt atoms to bind to the support, and therefore, if Pt atoms bind more strongly with Ge, they may be expected to weaken bonding with the surface. It also correlates with the quenched spins on the Pt, indicative of strong polar-covalent Pt-Ge bonding. However, to lose one Ge atom is the hardest for Pt 4 Ge, which exhibits an enormous E D (Ge) of 4.20 eV. Overall, Pt 4 Ge is the cluster composition that will offer the largest resistance against both main sintering mechanisms, and hence, adding small quantities of Ge would aid in reducing the sintering in Pt nanoparticles. The fact that this stoichiometry was most easily obtained in the recent experiments correlates both with this result, and with the phase diagram shown in Figure .