Category:XAS: Difference between revisions

Revision as of 09:14, 18 February 2025

X-ray absorption spectroscopy (XAS) comes in many flavors. One of the most important is X-ray absorption near-edge spectroscopy (XANES). XANES is a very strong (and experimentally heavily used) method for the characterization of materials. The simulation involves the excitation of a core electron into valence/conduction bands. Since the electron stays strongly localized on the atom for most semiconductors and insulators, the inclusion of electron-hole interactions in the calculations is absolutely crucial. Two methods are mainly used:

Super-cell core-hole (SCH) method ^[1].
Bethe-Salpeter equation (BSE) method.

To get familiarized with XAS or XANES calculations one should read the theory behind the method and do the following tutorial: XAS - Tutorial. The how to gives an overview of the steps needed to perform XAS calculations within the super cell.

Theoretical background

Theoretical backroung for XAS calculations: XAS theory.

How to

XAS (XANES) spectra from the super-cell core-hole method: SCH calculations.

Tutorial

Tutorial to perform XAS calculations: XAS - Tutorial.

↑ F. Karsai, M. Humer, E. Flage-Larsen, P. Blaha, and G. Kresse, Phys. Rev. B 98, 235205 (2018).

Pages in category "XAS"

The following 12 pages are in this category, out of 12 total.

B

Bethe-Salpeter equation for core excitations

C

I

ICORELEVEL

S

[karsai:prb:2018-1] F. Karsai, M. Humer, E. Flage-Larsen, P. Blaha, and G. Kresse, Phys. Rev. B 98, 235205 (2018).

[1]

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-'''Important''': All XAS are only available from VASP.6.0 or higher.
+X-ray absorption spectroscopy (XAS) comes in many flavors. One of the most important is X-ray absorption near-edge spectroscopy (XANES).
+XANES is a very strong (and experimentally heavily used) method for the characterization of materials.
+The simulation involves the excitation of a core electron into valence/conduction bands. Since the electron stays strongly localized on the atom for most semiconductors and insulators, the inclusion of electron-hole interactions in the calculations is absolutely crucial. Two methods are mainly used:
+*Super-cell core-hole (SCH) method {{cite|karsai:prb:2018}}.
+*Bethe-Salpeter equation (BSE) method.
-To get familiarized with X-ray absorption spectroscopy (XAS) calculations one should read the theory behind the method and do the following tutorial: {{TAG|XAS - Tutorial}}.
+To get familiarized with XAS or XANES calculations one should read the theory behind the method and do the following tutorial: {{TAG|XAS - Tutorial}}.
-Currently only the super-cell core-hole method is implemented in VASP for XAS.
 The [[:SCH calculations|how to]] gives an overview of the steps needed to perform XAS calculations within the super cell.