Electronic structure and physical properties of ABC(2) (A = Zn, B = Si, Ge, Sn, and C = P, As) ternary pnictide semiconductors

Band structure calculations of ABC(2) (A = Zn, B = Si, Ge, Sn, and C = P, A s) ternary pnictides performed using the semi-relativistic 'tight binding l inear muffin tin orbital' (TB-LMTO) method within local density approximati on under ambient and high pressures are reported here. The energy gap at am bient pressure is found to be direct in all the cases and the nature of the gap crucially depends on the manner in which the d electrons of atom A are treated. The equilibrium lattice constants, the bulk modulus, its first de rivative and the metallisation volume obtained from the total energy calcul ations are also reported. More generalized equations connecting cell volume (V-0) and microhardness (H) as well as V-0 and melting point (theta (m)) f or pnictides are established, by use of which the values of H and theta (m) for some pnictides are predicted for the first time in cases where experim ental values are not known.