We report metal-encapsulated caged clusters of silicon from ab initio pseudopotential plane wave calculations using generalized gradient approximation for the exchange-correlation energy. Depending upon the size of the metal (M) atom, silicon forms fullerenelike M@Si16, M = Hf, Zr, and cubic M@Si14 M = Fe, Ru, Os, caged clusters. The embedding energy of the M atom is ≈ 12 eV due to strong M − Si interactions that make the cage compact. Bonding in these clusters is predominantly covalent and the highest-occupied–lowest-unoccupied molecular orbital gap is ≈ 1.5 eV. However, an exceptionally large gap (2.35 eV) is obtained for Ti@Si16 Frank-Kasper polyhedron. Interaction between these clusters is weak, making them attractive for cluster-assembled materials.
ASJC Scopus subject areas
- Physics and Astronomy(all)