Structural and electronic properties of metal-encapsulated silicon clusters in a large size range.

Structural and electronic properties of metal-doped silicon clusters MSi(n)s (M=W, Zr, Os, Pt, Co, etc.) in a large size range of 8<or=n<or=20 are investigated via ab initio calculations. Different from a recent experimental suggestion that the metal atom is endohedral in MSi(n), we reveal that the formation of endohedral structure strongly depends on the size of the Si(n) cluster. Two novel structures of the chemically stable endohedral species are manifested. The suitable M@Si(n) building blocks of self-assembly materials vary in the range of 10<or=n<or=16. The thermodynamical magic numbers are found to coincide with the chemical magic numbers for five clusters.