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Electronic structure and excitations in oxygen deficient CeO_(2-δ) from DFT calculations

机译:DFT计算得出缺氧CeO_(2-δ)中的电子结构和激发

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The strongly correlated electron systems; heavy fermionss of supercells of CeO_(2-δ) have been calculated within the density functional theory (DFT). The equilibrium properties such as lattice constants, bulk moduli, and magnetic moments are well reproduced by the generalized gradient approximation (GGA). Electronic excitations are simulated by robust total-energy calculations for constrained states with atomic core holes or valence holes. Pristine ceria CeO_2 is found to be a nonmagnetic insulator with magnetism setting in as soon as oxygens are removed from the structure. In the ground state of defective ceria, the Ce-f majority band resides near the Fermi level but appears at about 2 eV below the Fermi level in photoemission spectroscopy experiments due to final-state effects. We also tested our computational method by calculating threshold energies in Ce-M_5 and O-K x-ray absorption spectroscopy and comparing theoretical predictions with the corresponding measurements. Our result that f electrons reside near the Fermi level in the ground state of oxygen-deficient ceria is crucial for understanding the catalytic properties of CeO_2 and related materials.
机译:高度相关的电子系统;在密度泛函理论(DFT)中已经计算出了CeO_(2-δ)超级电池的重费米子。广义梯度近似(GGA)很好地再现了诸如晶格常数,体模和磁矩之类的平衡特性。通过对原子核孔或价孔的受约束状态进行鲁棒的总能计算,可以模拟电子激发。发现原始二氧化铈CeO_2是一种非磁性绝缘体,一旦从结构中除去氧气,其磁性便会凝固。在有缺陷的二氧化铈的基态中,Ce-f多数谱带位于费米能级附近,但由于最终状态的影响,在光发射光谱实验中出现在费米能级以下约2 eV处。我们还通过计算Ce-M_5和O-K x射线吸收光谱中的阈值能量并将理论预测值与相应的测量值进行比较来测试我们的计算方法。我们的研究结果表明,在缺氧二氧化铈的基态中,f电子位于费米能级附近对理解CeO_2和相关材料的催化性能至关重要。

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