The orthorhombic Ca//3Al//2Si//2 structure contains well-separated parallel Al//2Si//2**6** minus chains which extend infinitely in one dimension. The chains resemble structurally the organic polymer polyacene but are more electron-rich. The similarities and the differences in the electronic structure of the two polymers, inorganic and organic, can be appreciated following two constructions of the band structure of the system. Within each chain there are two nonequivalent lattice sites: a twofold one and a threefold one. Three possible ways of assigning Al and Si atoms to these sites are examined. The preferred and realized choice is that all Si atoms reside in the twofold sites, all Al atoms in the threefold ones. A rationale for this is given.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry