TOTAL-ENERGY CALCULATION FOR CDXSN1-XTE

In the mixed crystal system CdxSn1-xTe, the transition from a ten-elec tron (x=0) to an eight-electron system (x=1) is realized, which is acc ompanied by a change in the crystal structure from rocksalt (SnTe) to zincblende (CdTe). The structure and lattice constants of solid soluti ons, grown (in part under high pressure) for nearly the whole mixing r ange, are known. We use norm-conserving pseudopotentials in connection with the local density and virtual crystal approximation for ab initi o calculations of the stable crystal structure and the lattice constan t in dependence on the composition x of the system. Our calculated res ults confirm Vegard's rule and give a crossover from rocksalt to zincb lende at about x=0.9 in accordance with experimental data. The crossov er is accompanied by a change in the binding character, which can be s een in a change of the electronic charge density.