Comparison of a calculated and measured XANES spectrum of α-Fe2O3.
Comparison of a calculated and measured XANES spectrum of α-Fe2O3.
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DOI：
10.1039/c1cp00034a
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
P. Canepa;E. Schofield;A. Chadwick;M. Alfredsson
中科院分区：
文献类型：
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作者：
P. Canepa;E. Schofield;A. Chadwick;M. Alfredsson
实验XANES谱的比较和预测是对所用电子结构计算质量的很好衡量，以及它们预测固体中电子跃迁的能力。本文对α-Fe(2)O(3)(赤铁矿)的几何、磁性和电子结构进行了BLYP+U和HYED-BLYP计算的比较。我们筛选了几个U值和不同的Fock交换百分数，以了解它们的贡献如何影响赤铁矿的不同性质，特别是电子结构。为了评估各种方法的质量，计算的态密度与实验收集的铁K边的XANES谱进行了比较，提供了描述导带的轨道的信息。我们发现，DFT+U和混合泛函模拟可以正确地预测价带的性质，但只有大于30%的Fock交换或等于或大于6 eV的U值才能正确地再现导带中t(G)和e轨道之间的顺序，因此，可以用来研究和预测赤铁矿的XANES谱和电子跃迁。
Comparison and prediction of the experimental XANES spectrum is a good measurement of the quality of the electronic structure calculations employed, and their ability to predict electronic transitions in solids. Here we present a comparison between BLYP + U and hybrid-BLYP calculations regarding the geometric, magnetic and electronic structures of α-Fe(2)O(3) (hematite). Several values of U and different percentages of Fock-exchange have been screened to see how their contributions affect different properties of hematite, paying particular attention to the electronic structure. To estimate the quality of the various methods the calculated density-of-states were compared to the experimentally collected XANES spectrum of the iron K-edge, providing information about the orbitals describing the conduction band. We find that in agreement with previous studies DFT + U and hybrid-functional simulations can correctly predict the character of the valence band, but only Fock-exchange higher than 30% or U-values equal or larger than 6 eV properly reproduce the order between the t(g) and e orbitals in the conduction band, and can, therefore, be used to study and predict XANES spectra and electronic transitions in hematite.