研究目的
To compare the structural and electronic properties of ZnO with other theoretical and experimental studies using the Siesta package program and to complement the lack of literature.
研究成果
ZnO exhibits phase transitions from B4 to B1 at 9 GPa and from B1 to B2 at 119.5 GPa, with intermediate states identified. All phases are semiconducting with band gaps of 0.69 eV (B4), 1.99 eV (B1), and 0.98 eV (B2). The B4 and B1 phases are mechanically and dynamically stable, while B2 is unstable. The study provides insights into high-pressure behavior and complements existing literature.
研究不足
The predicted phase transition pressures may differ from experimental results due to infinite volume defect assumptions, finite simulation cell size, and time scale constraints. The Pm(cid:2)3m phase is mechanically and dynamically unstable.
1：Experimental Design and Method Selection:
Ab initio calculations using the SIESTA package program with GGA-PBE exchange-correlation function and double zeta basis set. Troullier-Martins norm-protective pseudo-potential used for electronic properties. Cutoff energy set to 300 Ryd. Energy-volume relationships calculated using conjugate gradient technique with pressure increased in 10 GPa steps.
2：Sample Selection and Data Sources:
ZnO crystal structures (B4, B1, B2 phases) simulated with 72-atom supercells under periodic boundary conditions.
3：List of Experimental Equipment and Materials:
Computational software (SIESTA, KPLOT, RGS algorithm, Crystalmaker) for calculations and visualization.
4：Experimental Procedures and Operational Workflow:
Equilibrate ZnO at zero pressure, apply pressure gradually, analyze phase transitions, calculate electronic band structures, density of states, elastic constants, and phonon dispersion curves.
5：Data Analysis Methods:
Fitting energy-volume data to Birch-Murnaghan equation of state, enthalpy calculations for transition pressures, stability conditions for elastic constants, and phonon analysis for dynamical stability.
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