Density-functional investigation of metal-silicon cage clusters MSin (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; n=8-16)

The geometries, stabilities, electronic, and magnetic properties of the transition metal encapsulated MSin (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; n = 8-16) clusters have been systematically investigated by using density functional theory with generalized gradient approximation. It is shown that every transition metal atom (TMA) will fall into the center of Si outer frame and form a metal-encapsulated Si cage at a certain size (ScSi14, TiSi12, VSi12, CrSi12, MnSi11, FeSi10, CoSi10, NiSi10 CuSi12, and ZnSi14). The size of the smallest cagelike structures cannot be determined by the radius of the TMA alone; the bonding properties and the orbital hybridization between TMA and Si atoms also play an important role. The stability of the cagelike MSin clusters cannot be understood by electron shell filling (18 or 20 electrons) rule; it depends on other factors. The total magnetic moments of MSin clusters and the magnetic moments of TMA in MSin clusters are not always quenched when the TMA falls into the center of the Si outer frame.