Electronic structure and hybridization of CaS by means of X-ray absorption spectroscopy at Ca and S K-edges.
Electronic structure and hybridization of CaS by means of X-ray absorption spectroscopy at Ca and S K-edges.
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DOI：
10.1107/s0909049512040617
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发表时间：
2013
影响因子：
2.5
通讯作者：
Wei Xu;Li-juan Liu;M. Cui;Lei Zheng;Yongfeng Hu;A. Marcelli;Ziyu Wu
中科院分区：
文献类型：
--
作者：
Wei Xu;Li-juan Liu;M. Cui;Lei Zheng;Yongfeng Hu;A. Marcelli;Ziyu Wu
立方硫化钙 (CaS) 是一种众所周知的系统，也是许多发光技术应用中有吸引力的构建块材料。然而，为了优化应用而设计其能带结构，必须准确理解其电子结构。本文通过在 Ca 和 S K 边缘进行的 X 射线吸收光谱研究了 CaS 的电子结构，并在多重散射理论和有限差分法的框架下进行了计算。在 Ca K 边，讨论了异常 d 态特征的存在，而在 SK 边谱中，指出了由于 Ca d 态和 S p 态之间的杂化而导致的前边肩的存在。尽管 CaS 的 l 投影态密度与之前的第一性原理计算非常一致，但标准松饼罐电势不足以在该系统中重现 Ca 和 S K 边缘的近边缘结构。事实上，CaS 具有高度对称性和不太紧凑的结构，其特点是具有大量共线原子构型，这对原子势的构造构成了严格的限制。相反，没有松饼罐近似的有限差分法更适合该系统中的X射线吸收计算。
The cubic calcium sulfide (CaS) is a well known system and an attractive building block material for many luminescence technological applications. However, it is essential to achieve an accurate understanding of its electronic structure in order to engineer its band structure for optimized applications. Here a study of the electronic structure of CaS by means of X-ray absorption spectroscopy performed at both Ca and S K-edges, and calculations performed in the framework of the multiple-scattering theory and of the finite difference method are presented. At the Ca K-edge the presence of an anomalous d states feature is discussed while in the S K-edge spectrum the presence of a pre-edge shoulder owing to the hybridization among Ca d states and S p states is pointed out. Although the l-projected density of states of CaS is in good agreement with previous first-principles calculations, the standard muffin-tin potential is inadequate to reproduce near-edge structures at both Ca and S K-edges in this system. Indeed, with its highly symmetric and less compact structure, CaS is characterized by a large set of collinear atomic configurations that pose severe constraints on the construction of the atomic potential. On the contrary, the finite-difference method with no muffin-tin approximation is more suitable for X-ray absorption calculations in this system.