First principles description of shell structure in metal clusters

The magic numbers were observed in alkali-metal clusters. In order to explain this striking phenomenon, a spherical jellium model was introduced. This phenomenological model successfully explained the appearance of magic numbers in terms of shell structure, like the shell model in the nuclear theory. For this model Sugino and Kamimura raised questions, asking if a shell structure really exists in small clusters or why the stable shapes of metal clusters are always spherical or spheroidal. Then they performed first-principles calculations for lithium clusters LiN with N = 4 to 36 for obtaining the stable structures of clusters. In this paper their theoretical treatment is reviewed. (author)