Paper NS2+EM-WeA2
A Periodic Table of Silicon-Metal Nano-Templates for Cluster-Assembled Materials

Wednesday, October 17, 2007, 2:00 pm, Room 616

The structure and bonding properties of MSi_n clusters, containing 1 to 14 Si atoms together with one transition metal atom among 24 different elements: Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ti, Zr, Hf, V, Nb, Ta, Ni, Pd, Pt, Cu, Ag, Au, were studied by first-principles calculations. Some of these clusters are known to have been synthesized. The transition metal atoms work as nucleation sites for MSi_n. We find that species with n =3, 5, 7, 10, 12 are stable and exhibit shapes independent on the metal atom envolved which establishes a systematic behavior for MSi_n. For most metals, due to p-d orbital hybridization, both MSi₁₂ and MSi₁₀ (the smallest endohedral species) are highly symmetric, exhibiting the shapes of a hexagonal prism (D_6h) and of a bicapped tetragonal antiprism (D_4d), respectively. For such clusters, we predict similar packing rules, but considerably different electronic properties. Nano-wires (hexagonal nano-cylinders) assembled from MSi ₁₂are stable and with tunable electronic properties. These attributes suggest MSi_n as building blocks for cluster assembled materials. We have systematized the results on MSi_n by the organization of the transition metals in the Periodic Table.