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 band structure calculations within the local-density approximation. At ambient pressure, ZnSe is a direct band gap semiconductor with the zinc-blende structure, Under compression, the direct band gap at Gamma increases and eventually is replaced by the indirect gap at X. At about 15 GPa, the zinc-blende structure becomes unstable and transforms into the rock salt structure, which is metallic in nature. Theoretical results fully substantiate the recent experimental observation of the metallization of ZnSe at pressures higher than 13 GPa.