Self-interaction-corrected local density approximation pseudopotential calculations of the structural phase transformations of ZnO and ZnS under high pressure

The structural phase transformations under high pressure of ZnO and ZnS have been investigated by using the Vogel-Krüger-Pollmann (VKP) scheme, in which the electronic self-interaction correction to the local density approximation (LDA) is introduced in a non-self-consistent manner within the pseudopotential approach. In these calculations, I have used highly optimized pseudopotentials and a plane-wave expansion of the wavefunctions. Moreover, the electronic structures of the zinc-blende (ZB) and rock-salt (RS) phases of both compounds have been similarly calculated. It has been found that the VKP scheme provides a highly improved description, relative to the LDA results, for the structural and electronic structure properties of the considered systems. However, the so-calculated transition pressures of the ZB-to-RS transition for both ZnO and ZnS are found to be significantly larger than the experimental data. RS-ZnO is predicted to be an indirect-gap semiconductor, with a wide band gap of 4.2 eV.