First-Principle Study of Zinc Sulfide (Zinc Blende, Rock Salt and Wurtzite): Stability,
Phase Transition and Structural Parameters
The research investigates the stability, phase transition and structural parameters of zinc sulfide (Zinc blende, Rock salt and Wurtzite) using first-principle. The study employs generalized gradient approximation (GGA) within density functional theory (DFT) in which ultra-soft pseudopotential (Zn.pbe-van.UPFb and S.pbe-van_bm.UPFc ) were used for both zinc and sulfide respectively. Self-consistent calculation was made using cut-off energies of 26Ry (~350 eV) and 180 Ry (~2450eV) for the cut-off wave function within the convergence accuracy of ~1mRy with respect to total energy and 0.5kbar in case of pressure. The results obtained show that Wurtzite is more stable because it has lowest energy among the three structures, there is transition from zinc blende to rock salt and from Wurtzite to rock salt with transition pressures of 17.5GPa and 16.9GPa respectively and all the three polymorphs are semi-conductors due to their band gap.