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

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arXiv · 0906.0897

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

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Abstract

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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Christos Gougoussis, Matteo Calandra, Ari P. Seitsonen, Francesco Mauri. 2009-06-29. First principles calculations of X-ray absorption in an ultrasoft pseudopotentials scheme: from $α$-quartz to high-T$_c$ compounds. https://arxiv.org/abs/0906.0897

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