Ab initio wave function-based methods for excited states in solids: Correlation corrections to the band structure of ionic oxides
Ab initio wave function-based methods for excited states in solids: Correlation corrections to the band structure of ionic oxides
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基于波函数的固体激发态方法：离子氧化物能带结构的相关校正
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
H. Stoll
中科院分区：
文献类型：
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作者：
L. Hozoi;U. Birkenheuer;P. Fulde;A. Mitrushchenkov;H. Stoll
应用从头算波函数方法研究了电子相关对氧化物体系能带结构的影响。我们选择氧化镁作为闭壳离子氧化物的原型。我们的分析基于局部哈密顿方法，并对从无限固体中切割出来的有限碎片进行了分析。局部化的万尼尔函数和嵌入势由先前的周期性Hartree-Fock HF计算得到。我们研究了各种电子相关效应在减小高频带隙和改变带宽中的作用。计算了现场和最近邻电荷弛豫以及远程极化效应。虽然相关效应对于计算精确的带隙是必不可少的，但我们发现它们对高频带宽产生较小的变化，至少对于这种材料来说是这样。令人惊讶的是，o2p价带得到了展宽效应。从头算的数据与热反射和x射线光发射实验得出的能隙和带宽很好地吻合。结果表明，这里应用的基于波函数的方法可以很好地控制近似和透明地识别决定电子能带结构的微观过程。
Ab initio wave function-based methods are applied to the study of electron correlation effects on the band structure of oxide systems. We choose MgO as a prototype closed-shell ionic oxide. Our analysis is based on a local Hamiltonian approach and performed on finite fragments cut from the infinite solid. Localized Wannier functions and embedding potentials are obtained from prior periodic Hartree-Fock HF calculations. We investigate the role of various electron correlation effects in reducing the HF band gap and modifying the bandwidths. On-site and nearest-neighbor charge relaxation as well as long-range polarization effects are calculated. Whereas correlation effects are essential for computing accurate band gaps, we found that they produce smaller changes on the HF bandwidths, at least for this material. Surprisingly, a broadening effect is obtained for the O 2p valence bands. The ab initio data are in good agreement with the energy gap and bandwidth derived from thermoreflectance and x-ray photoemission experiments. The results show that the wave function-based approach applied here allows for well controlled approximations and a transparent identification of the microscopic processes which determine the electronic band structure.