Role of the substrate dynamics: Iron clusters deposited on an iron slab

The deposition of iron clusters on an iron substrate is investigated by means of classical molecular dynamics. The substrate dynamics is incorporated and shown to be a relevant ingredient, which leads to substantial changes of the transition temperatures, and of the thermodynamics of the cluster substrate interacting system. Fe55 clusters on Fe (110) and (111) reconstructed surface orientations were studied, showing a stronger effect of the substrate dynamics for the (111) orientation. In fact, the melting temperature for a free Fe cluster, obtained by molecular dynamics simulations, is of the order of 1000 K, significantly lower than the 1812 K of bulk iron. When supported on a rigid Fe substrate it corresponds to ≈ 1400 K on both the (110) and (111) orientations. However, when the substrate dynamics is incorporated, the melting temperature changes markedly to ≈ 1200 K on the (110), and to ≈ 900 K on the (111), Fe substrate orientation.