First, adatoms were randomly distributed on the 100×100 (100) surface at different surface coverages (i.e. 0.5 ML, 0.25 ML, 0.125 ML, and 0.0625 ML) to study nucleation and aggregation processes on metallic sodium and lithium. All systems were evaluated at 100 K, 200 K, 300 K, and 400 K, respectively. Snapshots from the kMC simulation of the initial growth and aggregation processes for both metals are given in Fig. . Initially, nucleation seeds are formed on the surface of both metals after a few nanoseconds. These nuclei gradually form small islands and keep growing continuously. Aggregation of islands is observed until only one individual round-shaped island remains on the surface after a few seconds. The nucleation processes occur within a few nanoseconds at all investigated temperatures due to the low terraced diffusion barrier; however, the growth rate of the islands is highly temperature-dependent. While terrace self-diffusion and migration along step-edges are almost barrier-free on both surfaces , the detachment barrier of an adatom perpendicular to the step is hindered by increased activation energies. Any temperature increase improves the probability of processes with higher diffusion barriers.