AB-INITIO CALCULATION OF ELECTRONIC-STRUCTURE AND STRUCTURAL-PROPERTIES OF ZNSEXTE1-X

The ternary mixed crystal system ZnSexTe1-x has recently attracted ren ewed interest as basic material for the blue/green laser diode. We use norm-conserving pseudopotentials in connection with the local density and virtual crystal approximation for ''ab-initio'' calculations of t he stable crystal structure and the lattice constant in dependence on the composition x of the system. Our results are in quantitative agree ment with structural properties but we find a bowing in the bandgap mu ch smaller than in the experimental data. To check the quality of our results, we use pseudopotentials which either consider the d-electrons of Zn in the core or treat them explicitly as valence electrons.