Ab initio study of the phase transformations of ZnSe under high pressure: stability of the cinnabar and SC16 phases

The structural phase transformations of ZnSe under high pressure are studie d by using a first-principles pseudopotential method and the local density approximation for the exchange-correlation potential. A new phase, which is simple cubic with a 16-atom basis (SC16), is predicted to be thermodynamic ally stable between 9.2 and 16.4 GPa, which is below the stability pressure range of the rock-salt structure. The cinnabar structure of ZnSe is found to be unstable, contrary to the findings of a previous theoretical investig ation. The structural properties of the zinc-blende, rock-salt, cinnabar an d SC16 phases are presented.