Core level spectroscopy: XPS, XAS, EELS, XES (XSPEC ... - WIEN 2k

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“Final state rule”: “Final state” determines the spectrum: • Emission spectroscopy: Final state has filled core, but valence hole. This is usually well screened, thus one “sees” the groundstate. • Absorption spectroscopy: Final state has a “hole” in core state, but additional e - in conduction band. Core-hole has large effect on the spectrum • electron – hole interaction, “excitonic effects” .
Treating the core hole within WIEN2k • No core hole (= ground state, sudden approximation) • usually not a good approximation (maybe in metals ) • Z+1 approximation (eg., replace C by N) • also not very good • Core-hole (supercell) calculations: • Remove 1 core electron on ONE atom in the supercell, add 1 electron to conduction band • Remove 1 core electron, add 1 electron as uniform background charge • considers statically screened e - - h coulomb correlation • Fractional core hole (consider different screening) • Explicit treatment of electron-hole interaction (excitonic effects) using Bethe-Salpeter equation (BSE)
Page 1 and 2: Core level spectroscopy: XPS, XAS,
Page 3 and 4: XAS (XANES), EELS (ELNES), XES: •
Page 5 and 6: Difference between EELS and XAS
Page 7: dipole approximation (TELNES3 can a
Page 11 and 12: XAS / TELNES in WIEN2k define your
Page 13 and 14: TELNES3 task
Page 15 and 16: • aaa Angle dependency of B-K edg
Page 17 and 18: L 2,3 spectra: failure of the singl
Page 19 and 20: fully relativistic electron-hole in
Page 21 and 22: L 2,3 edge for Ca in CaF 2 L 3 L 2
Page 23 and 24: Ti L 2,3 in SrTiO 3 , decomposition
Page 25 and 26: fcc Ca, L 2,3 edge L 3 L 2 L 2 L 3

Core level spectroscopy: XPS, XAS, EELS, XES (XSPEC ... - WIEN 2k

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