NA CLUSTERS ON NA-CL SURFACES - THE IMPACT OF THE INTERFACE POTENTIAL

We investigate the structure and energetics of Na clusters on Na-Cl su rfaces. The Na-Cl substrate is taken as inert acting on the clusters c onstituents essentially through its interface potential which consists in a general surface attraction and is modulated by corrugation. The cluster is described as a predominantly electronic system in the spiri t of the ultimate jellium model. The strong surface attraction makes p lanar clusters the preferred choice in any case and non-planar stable isomers do always exist. The corrugation has a large influence on the shapes, particularly for the larger clusters. But the total energy of the clusters is insensitive to these details. It can be described in t erms of volume, surface, and interface energy allowing a simple estima te of the preferred geometry in dependence of the strength of the inte rface potential.