Dodecahedral Clusters and Novel Cubic Allotropic Forms of Carbon, Silicon, and Germanium: Computer Simulation

• Published in: Fullerenes, nanotubes, and carbon nanostructures nanotubes, and carbon nanostructures, 2006-12, Vol.14 (2-3), p.527-531
• Main Authors: Stankevich, Ivan V., Chistyakov, Anatolii L., Korlyukov, Alexandr A.
• Format: Article
• Language: English
• Subjects: crystal [X; DFT; dodecahedral clusters C; energy gap; Fullerenes; PBE96/FLAPW
• ISSN: 1536-383X; 1536-4046
• DOI: 10.1080/15363830600666530

A method is described for building up novel three-dimensional periodical structures consisting of atoms C, Si or Ge. Polyhedral dodecahedral shape clusters X 20 are basis of such lattices. Three-dimensional nets with simple cubic lattices can be produced on the base of X 20 clusters. Each cluster X 20 has six neighboring clusters X 20 . Two neighboring clusters are bound by two covalent bonds. It is found that large size cavities are contained in such structures. Cubic clusters X 8 can be disposed in these cavities. Each cluster X 8 has eight neighboring clusters X 20 and is covalently linked with one of these clusters. As a result, periodical crystalline structures [X 8 @(X 20 ) 8 ] n (or [X 28 ] n ) with simple cubic lattice can be produced. The lattice parameters of these crystals were found using DFT-PBE optimized calculations of clusters X 8  @ (X 20 ) 8 and X 8  @ (X 20 H 13 ) 8 . Structure of the [C 28 ] n crystal was obtained more accurate by the PBE96/FLAPW method. Calculations of density of states show that the crystal is dielectric with an energy gap of 3.3 eV.