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arXiv 0906.0897cond-mat.mtrl-scicond-mat.str-el
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超软赝势方案中X射线吸收的第一性原理计算:从$α$ -石英到高T $_c$化合物

First principles calculations of X-ray absorption in an ultrasoft pseudopotentials scheme: from $α$-quartz to high-T$_c$ compounds

Christos Gougoussis, Matteo Calandra, Ari P. Seitsonen, Francesco Mauri

摘要:

基于连分数方法和超软赝势,发展了一种计算固体K边X射线吸收谱的第一性原理方法.该方法允许计算的K-边X射线吸收光谱的过渡金属和稀土化合物与大大减少截止相对于正常保存的情况下。我们通过计算$α$石英中Si和O的K边、Cu中Cu的K边和La $_2$ CuO $_4$中Cu的K边来验证该方法。对于硅和O边的情况下,在$α$石英和铜,我们得到了很好的协议与实验数据。在La $_2$ CuO $_4$(一种被认为是密度泛函理论的实能材料)的Cu K边谱中,我们把所有的近边和远边峰都归因于单粒子激发。

英文摘要:

We develop a first-principles scheme based on the continued fraction approach an d ultrasoft pseudopotentials to calculate K-edge X-ray absorption spectra in solids. The method allows for calculations of K-edge X-ray absorption spectra in transition metal and rare-earths compounds with substantially reduced cutoffs respect to the norm-conserving case. We validate the method by calculating Si and O K-edges in $α$ quartz, Cu K-edge in Copper and in La$_2$CuO$_4$. For the case of Si and O edges in $α$ quartz and in Copper we obtain a good agreement with experimental data. In the Cu K-edge spectra of La$_2$CuO$_4$, a material considered a real challeng e for density functional theory we attribute all the near-edge and far-edge peaks to single particle excitations.

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