First-principles study on incidence direction, individual site character, and atomic projection dependences of ELNES for perovskite compounds
First-principles study on incidence direction, individual site character, and atomic projection dependences of ELNES for perovskite compounds
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DOI：
10.1016/j.ultramic.2005.06.006
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发表时间：
2006-01-01
期刊：
影响因子：
2.2
通讯作者：
Ikuhara, Y
中科院分区：
文献类型：
--
作者：
Mizoguchi, T;Buban, JP;Ikuhara, Y
用第一性原理能带计算方法，理论模拟了YBa2Cu3O7(YBCO)和SrTiO3的电致发光光谱(ELNES)的O-K近边精细结构的入射方向依赖关系、单位性质依赖关系和原子投影依赖关系。为了计算ELNES，在氧的轨道上引入了一个核心空穴，并使用了足够大的由100多个原子组成的超级单胞。我们发现，YBCO的O-K Elnes谱的第一峰强度强烈地依赖于原子的投影方向，当用其他的投影方向测量光谱时，强度消失。在SrTiO_3的O-K元素谱中也预测到了较大的投影依赖性。研究发现，这些随投影位置变化的光谱是由钛酸锶中的单向Ti-O-Ti键引起的。(C)2005 Elsevier B.V.保留所有权利。
The incidence direction dependence, the individual site character dependence, and the atomic projection dependence of O-K near edge fine structure of the EEL spectrum (ELNES) from YBa2Cu3O7 (YBCO) and SrTiO3 were theoretically simulated using the first-principles band structure calculation. In order to calculate ELNES, a core-hole was introduced at the oxygen Is orbital, and sufficiently large supercells composed of more than 100 atoms were employed. We found that the intensity of the first peak of O-K ELNES from YBCO strongly depends on the atomic projection direction, and disappears when the spectrum is measured with the other projection directions. The large projection dependence was also predicted in the O-K ELNES of SrTiO3. It was found that those spectral changes according to the position of the projection are caused by the unidirectional Ti-O-Ti bond in SrTiO3. (c) 2005 Elsevier B.V. All rights reserved.