研究目的
Investigating the electronic and optical properties of CaO: Eu+2 (SrO: Eu+2) phosphors compounds using first-principles density functional theory (DFT) and DFT+U calculations.
研究成果
The study successfully applied first-principles DFT and DFT+U calculations to investigate the electronic and optical properties of CaO: Eu+2 (SrO: Eu+2) phosphors. The results showed that the appearance of Eu-4f states at the valence band maximum of the spin-up significantly impacts the electronic properties of the compounds. The optical spectral structure demonstrated a lossless region and uniaxial anisotropy. The calculated values were in good agreement with experimental results, validating the effectiveness of the GGA+U approach in describing the electronic band energy.
研究不足
The GGA+U approach is highly expensive in terms of computation due to the interaction of d or f electrons. The study also mentions the use of arbitrary values of U to treat the strongly correlated electrons, which may not always yield the most accurate results.
1:Experimental Design and Method Selection:
The study employed first-principles density functional theory (DFT) and DFT+U calculations using the generalized gradient approximation plus optimized effective Hubbard parameter U (GGA+U). The full potential linearized augmented plane wave plus local orbitals (FPLAPW+lo) method was applied in WIEN2k for crystal data optimization.
2:Sample Selection and Data Sources:
The study focused on CaO: Eu+2 (SrO: Eu+2) phosphors compounds with cubic symmetry.
3:List of Experimental Equipment and Materials:
The calculations were performed using the WIEN2k software.
4:Experimental Procedures and Operational Workflow:
The atomic positions were relaxed by reducing forces on each atom, and the structure was considered relaxed if the forces acting on it were less than 1 mRy/a.u. The calculations were performed using different values of U (
5:0, 0, 0, and 0 eV) to treat the strongly correlated electrons. Data Analysis Methods:
The partial density of states (PDOS) and total density of states (TDOS) were calculated using the modified tetrahedron method. The electronic band structure and other related properties were performed with 512 k-points in the irreducible Brillouin zone (IBZ).
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