ELECTRONIC-STRUCTURE OF THE LAYERED COMPOUNDS K[SNSB], K[SNAS] AND SR[SN2AS2]

The electronic band structure, the density of states, and the electronic charge density distribution of K[SnAs], K[SnSb], and Sr[Sn2As2] are studied by means of self-consistent density-functional calculations in the local approximation. The valence bands and the conduction bands are separated by a band gap which in one case (Sr[Sn2As2]) is nearly zero. The fully occupied valence bands can be identified as s- and p-like bands of Sn, As, and Sb. These results indicate that the alkali and alkaline earth atoms form a cationic substructure. The Sn and As/Sb atoms form covalent and negatively charged layer structures. The correlations between the Zintl concept and the calculated band structures are discussed. © 1992.