Exohedral silicon fullerenes: SiNPtN/2 (20<or=N<or=60).

Using density functional theory method we show that hollow silicon fullerene cages, SiN (20<or=N<or=60), can be fully stabilized by exohedrally coated platinum atoms (PtN/2), denoted as SiNPtN/2. The exohedral coating PtN/2 passivates the dangling bonds of the silicon cages, thereby making the silicon cages SiN to retain the symmetry and structure of homologous carbon fullerenes CN. In particular, the Ih symmetrical, 60-atom silicon buckminsterfullerene cage (Si60) can be fully stabilized by exohedrally coated 30 Pt atoms. Properties of SiNPtN/2, such as the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap and relative stability of cage isomers, are calculated and compared with their carbon counterparts. It is found that the HOMO-LUMO gaps of SiNPtN/2 are close to their carbon fullerene counterparts (CN). The trend in relative stability for exohedral fullerene isomers SiNPtN/2 is similar to that for the homologous carbon fullerenes (CN). The exohedral Pt coating offers a possible molecular design towards stabilizing the silicon fullerene cages.