[Pw_forum] Comparing xspectra to experimental data: absolute energy shift

[Hud Wahab]

Hello QE community

 

I am trying to compare the xspectra (5.3.0) and experimental absorption data
at the carbon K-edge, that is, the measured energies for carbon K-edge
between 285 eV and 320 eV.  How does one shift the xspectra simulation to
the absolute energy scale of the experiment?  I think that means getting an
element-specific absolute value of the energy shift.  I understand that the
calculated Fermi energy is one quantity we need to shift by - but this value
is nowhere near the ~285 eV needed to make a sensible comparison.

And, if the absolute value was element-specific, in this case for carbon, it
presumably comes from the generation of the pseudopotential and is hopefully
recorded in the pseudopotentil file (e.g.

C.star1s-pbe-mt_gipaw.UPF).  What are the units of the energy given in this
particular file?

"<PP_GIPAW_CORE_ORBITAL>

   1    0     N  L                       1S     eig:  -25.48712189"

 

-Hud

UNSW Canberra

 

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