论文标题
MGO的光学和X射线吸收光谱的理论描述包括多体效应
Theoretical description of optical and X-ray absorption spectra of MgO including many-body effects
论文作者
论文摘要
在这里，我们使用密度功能理论（DFT）和多体扰动理论（MBPT）报告了宽波段氧化物MGO的光学和X射线吸收（XAS）光谱。我们对电子结构的全面研究表明，尽管与实验值（7.7 eV）相比，频带差距低估了交换功能PBESOL（4.58 eV）和杂交功能性HSE06（6.58 eV）（7.7 eV），但它在Quasipiper上（8.53 ev）均得到了显着改进（7.52 eV），即Quasipipe recortions Quasipiper erisions。通过求解贝尔氨基盐方程（BSE）来包含激子效应，可以使光谱与实验非常吻合。对于O和Mg K边缘吸收光谱也可以观察到极好的一致性，这表明了MBPT中电子孔相互作用的重要性。从频带结构上BSE特征向量的电子孔耦合系数的投影使我们能够确定突出峰的起源并确定相关贡献的轨道特征。光谱的最低能量激子波函数的真实空间投影表明一种含量，而O K边缘中的第一个激子则更具位置。
Here we report the optical and x-ray absorption (XAS) spectra of the wide-band-gap oxide MgO using density functional theory (DFT) and many-body perturbation theory (MBPT). Our comprehensive study of the electronic structure shows that while the band gap is underestimated with the exchange-correlation functional PBEsol (4.58 eV) and the hybrid functional HSE06 (6.58 eV) compared to the experimental value (7.7 eV), it is significantly improved (7.52 eV) and even overcompensated (8.53 eV) when quasiparticle corrections are considered. Inclusion of excitonic effects by solving the Bethe-Salpeter equation (BSE) yields the optical spectrum in excellent agreement with experiment. Excellent agreement is observed also for the O and Mg K-edge absorption spectra, demonstrating the importance of the electron-hole interaction within MBPT. Projection of the electron-hole coupling coefficients from the BSE eigenvectors on the band structure allows us to determine the origin of prominent peaks and identify the orbital character of the relevant contributions. The real space projection of the lowest energy exciton wavefunction of the optical spectrum indicates a Wannier-Mott type, whereas the first exciton in the O K-edge is more localized.
