Structure and bonding in cubic IV-VI crystals. 1

The inherent instability of the cubic structure of IV-VI compounds is considered. Alternatively to the work of Littlewood, the treatment bases on the LCAO method and relates to Harrison's approach as Littlewood's papers do to Phillips'-Van Vechten's one. First Harrison's polarity is calculated from Slater-Koster parameters due to Volkov and coworkers. It indicates predominantly covalent bonding character for the cubic IV-VI compounds. A comparison is given with Littlewood's treatment. The method of special points is used to calculate integral bonding properties. Chadi and Cohen's two point set is shown to be often equivalent to a ligand-field theoretical treatment. (author)