研究目的
Investigating the polaronic configurations introduced by oxygen vacancy in rutile TiO2 crystal and how the density of oxygen vacancy influences these configurations.
研究成果
The study concludes that the most stable polaronic configuration in rutile TiO2 changes from small polaronic configuration to mixed configuration with increasing oxygen vacancy density, due to enhanced interaction between vacancies. This evolution is consistent with IR absorption spectrum observations. The findings highlight the importance of carefully testing supercell size in theoretical calculations to avoid finite size effects.
研究不足
The study is limited by the computational methods and models used, including the reliance on DFT + U for electron correlation correction and the finite size effect from mirrored defects in small supercell models.
1：Experimental Design and Method Selection:
The study employs the DFT + U method to correct the self-interaction error in standard DFT calculations. The Hubbard U correction is calculated using the linear response method.
2：Sample Selection and Data Sources:
Oxygen vacancy structures are constructed from supercells of different sizes (3 × 3 × 5, 3 × 3 × 4, and 2 × 2 × 3) by removing one oxygen atom from the crystal grid.
3：List of Experimental Equipment and Materials:
Calculations are performed using QUANTUM ESPRESSO (Version
4：1) with PBEsol GGA exchange correlation functional and PBEsol pseudopotentials. Experimental Procedures and Operational Workflow:
The study involves variable-cell relaxation processes with carefully examined cutoff energy and k-sampling to ensure total energy convergence. Polaronic configurations are obtained by elongating coordinated chemical bonds in the starting structure of geometrical relaxation.
5：Data Analysis Methods:
The study analyzes the electronic structure and stability of different polaronic configurations through density of state (DOS) calculations and Bader population analysis.
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