STABILITY OF CDXSN1-XTE IN ROCK-SALT STRUCTURE - A STUDY OF ZERO-FLUXSURFACES AND BONDING CHARACTER

In the mixed crystal system CdxSn1-x Te the transition from a ten (x = 0) to an eight-electron system (x = 1) is realized with a simultaneou s change from rocksalt (SnTe) to zinc blende structure (CdTe). From pr evious calculations using density functional theory (DFT) [in the loca l density approximation (LDA) together with normconserving pseudopoten tials and the virtual crystal approximation (VCA)] we know, that the r ocksalt structure is stable up to x = 0.93. As a possible reason for t his stability we investigate the valence charge transfer connected wit h the formation of the solid by employing the concept of zero-flux sur faces, which has been used so far only for molecules. We find an incre asing charge transfer when going form CdTe to SnTe in the rocksalt str ucture. In addition we analyze the bonding character of the individual valence bands and find partial antibonding for CdTe in zinc blende. B oth support the stability of the rocksalt structure, which is found ex perimentally.