On the Chemical Bonding in the Intermetallic B32-Type Compounds LiMe

The electronic charge distributions in the binary intermetallic B32 phases LiMe with Me = Zn, Cd. AI, Ga and In have been calculated by the relativistic augmented plane wave method. It is found that the character of the contribution from the various electron bands to the chemical bond is different for the lower valence bands and for the higher valence-conduction bands. The lower valence bands are occupied by two electrons per formula unit LiMe and are predominantly of covalent s-p-type, formed by the diamond-like sublattice of the Me atoms. For all compounds the percentage p-like character is smaller than for the sp hybrid within the molecular orbital picture. The valence bands above the covalent bands are s-p-like bands with enhanced metallic character. Besides a large covalent contribution to the chemical bond in the intermetallic B32-type phases, a charge transfer from the lithium atoms to the l ib and Ilia elements is found. The amount of charge transfer is distinctly smaller than one electron per formula unit LiMe. It is shown that the charge transfer is correlated to the differences in the electronegativities of the corresponding atoms.