MonS2n+x clusters—magic numbers and platelets

The electronic and structural properties of clusters (MonSm) of the layered semiconductor MoS2 are studied using density-functional based methods. For small MonSm clusters the evolution of structural elements, resembling the corresponding structure motifs of the layered bulk compound MoS2 was found. Among the small clusters a highly symmetric Mo4S6 cluster features an outstandingly high stability and a large HOMO–LUMO gap. This cluster can be characterized as a “magic cluster”. With increasing cluster size the stabilization of platelet structures is indicated. In the platelet structures the edges determine the deviation from the bulk properties. The binding energies increase smoothly with increasing cluster size towards the bulk limit. Small clusters and platelet structures have a HOMO–LUMO gap comparable with the gap of the semiconductor bulk material, whereas larger platelet structures show a metallic-like behavior.