AB-INITIO PSEUDOPOTENTIAL STUDY OF THE STRUCTURAL AND ELECTRONIC-PROPERTIES OF ZNTE UNDER HIGH-PRESSURE

We have performed ab initio pseudopotential calculations within the lo cal density approximation to investigate the structural phase transiti on of ZnTe under pressure. Zn 3d and Te 4d orbitals are treated as par t of the valence states in order to describe the structural properties of ZnTe accurately. By calculating the total energy, atomic force, an d stress tensors, we theoretically determine the structural phase tran sition of ZnTe from the zinc-blende (ZB) to the cinnabar to the distor ted NaCl structure under increasing pressure. Calculational results ar e compared in detail with the recent experimental data obtained using angle-dispersive techniques and an image-plate detector. We also demon strate that rotation of bonds toward lower-symmetry positions occurs a t the critical pressure to relieve excessive strain. Detailed electron ic structures of each phase are also presented.