Computational study of the structural phases of ZnO

Abstract

We use first-principles calculations based on density functional theory to study the structural properties and pressure-induced solid-solid phase transitions of ZnO. Both the local-density and the generalized gradient approximations are employed together with the projector augmented wave potentials to mimic the electron-ion interaction. We consider the wurtzite (B4), rocksalt (B1), zinc blende (B3), CsCl (B2), NaTl (B32), WC (B${}_{h}$), BN (B${}_{k}$), NiAs (B8${}_{1}$), and AsTi (B${}_{i}$) modifications of ZnO. The calculated structural properties in the B4, B3, B1, and B2 phases are in excellent agreement with earlier ab initiopredictions, as is the transition pressure between them. We find that the B4 phase is the most preferred low-pressure candidate in ZnO while the B2 phase is favorable at high pressures. Apart from the previously reported $B4\ensuremath{\rightarrow}B1\ensuremath{\rightarrow}B2$ phase transition, our study reveals other possible paths for a transition from the B4 to the B2 phase.