Self-consistent electronic structures and bond orbitals constructed from sp3-hybridized atom-centered orthogonal linear muffin-tin orbitals (LMTOs) are used to study the bonding properties of Zintl phases. Calculation of the relative bonding-antibonding character allows a study of trends in the bonding. The examination includes binary (LiM with M=B-Tl, NaIn, and NaTl) and ternary (LiAlSi) Zintl phases. In this way it is possible to obtain quantitative values for the 'degree of sp3 bonding' in these compounds. The trends follow those found in B2-B32 structural energy differences. Furthermore, by transforming the LMTOs to the localized basis the authors calculate the full non-spherical charge distributions.
 

Physical Review B, 34 7080-8, 1986.