The evolution of a cluster to its equilibrium shape where the number of particles in the cluster fluctuates around an average value. A typical initial cluster shape is shown in the inset on the left, and a typical equilibrated cluster shape is shown in the inset on the right where some freely diffusing particles on the surface are visible. The cluster resides on a square grid of lattice constantaof dimensions 350×350 in all simulations presented in this work. The energy parameters used in the simulation (unless otherwise indicated) are as follows (all in units of meV):E_b= 125,E_d= 150, andE_ds= 100. The grey color scale in the insets represents the height of the single atomic layer of the cluster, the lowest level being the darkest in the figure.