THEORETICAL-STUDY ON THE HIGH-PRESSURE PHASE-TRANSFORMATION IN ZNSE

The high-pressure phase transition in ZnSe has been examined with full -potential linear augmented plane wave and numerical atomic orbital ba nd structure calculations within the local-density approximation. At a mbient pressure, ZnSe is a direct band gap semiconductor with the zinc -blende structure, Under compression, the direct band gap at Gamma inc reases and eventually is replaced by the indirect gap at X. At about 1 5 GPa, the zinc-blende structure becomes unstable and transforms into the rock salt structure, which is metallic in nature. Theoretical resu lts fully substantiate the recent experimental observation of the meta llization of ZnSe at pressures higher than 13 GPa.