was not chosen as a starting cluster size for the sintering simulations, to ensure that, for each starting cluster size, Pt n , there exists an explicitly computed isomeric diversity of the size, Pt n±1 . For Pt 9+ clusters, the energies and shapes were extrapolated based on the linear function (Equation ( ) and ( ) as detailed in the SI). In order to only explore the sizedependent sintering effects, as opposed to coverage effects, we controlled the cluster-cluster distance to be 5 Åfor all sizes. 100 clusters were initially randomly deposited on the support in each case. As a result, the size of the Al 2 O 3 supercell was varied with starting cluster size.