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Establishment of the ab initio method for excited states and analysis of the anomalous X ray scattering spectra

激发态从头计算方法的建立及反常X射线散射谱分析

基本信息

批准号：
12640337
负责人：
IGARASHI Junichi
金额：
$ 0.38万
依托单位：
Gunma University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640337/
关键词：
Ab initio calculation Resonant x ray scattering orbital order Jahn-Feller distortion Transition-metal oxide Rare-earth metal compound 局所的電子相関

项目摘要

1. We have calculated the resonant x-ray scattering spectra near the vanadium K-edge in YVO_3 using an ab initio band calculation. Against a usually adopted interpretation that the intensity on the orbital ordering superlattice spot is a direct reflection of the ordering, we have found that the intensity comes from the lattice distortion, the Jahn-Teller type and the GdFeO_3 type. This is due to the extended nature of the 4p states of vanadium. Each type is found to play a different role on the spectral shape, in good agreement with the recent experiment.2. We have analyzed the resonant x-ray scattering spectra near Ce L_<III>-edge in the quadrupolar ordering phase of CeB_6 on the basis of a tight-binding model. Different from the case of transition-metal oxides, the intensity on the quadrupolar ordering superlattice spot is found to come from the 5d states modulated by the anisotropy of the charge distribution associated with the direction of the quadrupole moment through the 5d-4f Coulomb interaction.3. We have calculated the resonant magnetic x-ray scattering spectra near Ni K-edge in NiO, using a tight-binding model. It is found that the main peak due to the dipole transition arises from the 4p states orbitally polarized by the orbital moment at neighboring sites, and that the pre-edge peak due to the quadrupole transition arises directly from the 3d states having the orbital moment, in good agreement with the recent experiment.

1.用从头算方法计算了YVO_3中钒K边附近的共振X射线散射谱。针对通常认为轨道有序超晶格斑点上的强度是有序性的直接反映的解释，我们发现这种强度是由晶格畸变、Jahn-Teller型和GdFeO_3型引起的。这是由于钒的4p态的扩展性质。发现每种类型对光谱形状起着不同的作用，这与最近的实验结果吻合得很好.本文<III>在紧束缚模型的基础上，分析了CeB_6四极有序相的Ce L_ -边附近的共振X射线散射谱。与过渡金属氧化物的情况不同，四极有序超晶格斑点上的强度来自5d态，通过5d-4f库仑相互作用，由与四极矩方向相关的电荷分布的各向异性调制.本文用紧束缚模型计算了NiO中Ni K边附近的共振磁X射线散射谱。结果发现，由于偶极跃迁的主峰产生的4p态的轨道极化的轨道矩在相邻的网站，和由于四极跃迁的前边缘峰直接产生的3d态的轨道矩，在最近的实验符合得很好。