INTERPRETATION OF BAND-GAP, HEAT OF FORMATION AND STRUCTURAL MAPPING FOR SP-BONDED BINARY COMPOUNDS ON THE BASIS OF BOND ORBITAL MODEL AND ORBITAL ELECTRONEGATIVITY

An empirical relation between band gap and Zunger's orbital electronegativity in sp-bonded compounds is determined using a formula derived from the bond orbital model. The abscissa in the relation is constructed using Zunger's orbital electronegativity and average principal quantum number, and it is defined as the bonding parameter (Psi). It is indicated that the heat of formation of an sp-bonded compound can be given as a function of Psi, Zunger's orbital radii and compositional factor based on the effective concentration (the ratio of atomic fraction to number of Valence electrons). Structural maps of fundamental crystal structures (from B1 to B4) of AB compounds and nine different crystal structures of AB(2) compounds are also successfully constructed using the hybrid function (H-sp) and gap reduction parameter (S) as the coordinates, which are derived from Psi using the bond orbital model. H-sp and S are found to be excellent parameters for describing the bonding character of compounds.