[Wien] Calculating XPS spectra in Wien2k

[Peter Blaha]

In addition to Xaviers comments:

Yes, if you have eg. 2 oxygen atoms in your structure, the differences 
in the core energies should reflect pretty well the experimentally 
measurable core-level shifts.

If you want to calculate the core energies better you can use
a) Slater's transition state
b) delta-scf calculations

a) remove HALF a core electron from case.inc (add it to case.inm)
do an scf calculation. Now the (eigenvalue-EF) difference should be 
closer to experiment (expect errors of a few eV instead of 30)
b) You can also use a full core hole and compare E-tot of groundstate 
and excited state. Eventually this should be done in a supercell and 
only on one of the atoms the hole should be added to avoid hole-hole 
interactions.


Rocquefelte schrieb:
> Dear James,
> 
> If you want to compare valence XPS spectrum with the DOS deduced from 
> your Wien2k calculation, you will obtain a qualitative agreement.
> Concerning the core states, you may have access to the energy of these 
> states in the case.scfc file. These values are relative to the fermi 
> level given in the case.scf file.
> Thus you should modify these energies in such a way to have a fermi 
> level comparable to your XPS experiment (the top of the valence).
> 
> Here is an example based on TiO2 rutile :
> 
> - Energy of Ti 2p1/2 (2p* in scfc file) = -442.5 eV
> - Energy of Ti 2p3/2 (2p in scfc file) = -436.7 eV
> 
> - Energy of O 1s = -504.2 eV
> 
> These values should be compared to the following experimental XPS 
> binding energies (BE):
> 
> - BE Ti 2p1/2 = 464.4 eV
> - BE Ti 2p3/2 = 458.6 eV
> 
> - BE O 1s = 530.1 eV
> 
> So, as you can see, a strong deviation (of about 30 eV) is observed 
> between experimental and calculated data.
> However, I would believed that the deviation is smaller if you compare 
> different BE in a same structure.
> 
> Hope that this email will help you
> 
> Regards
> 
> 
> 
> James Enterkin a écrit :
>> Dear All,
>>
>> I was wondering if anyone would know how to go about calculating the 
>> energy of an XPS peak?
>> I have a converged structure, and would like to be able to calculate 
>> the binding energy of an electron on a specific atom in the structure, 
>> to see if it matches up with the shift in the experimental XPS of that 
>> same structure.
>> If anyone has previously done this or similar, or knows what method 
>> would be best to go about this, your suggestions would be most helpful.
>>
>> Thank you,
>> Jim
>>
>> --
>> James A. Enterkin
>> j-enterkin at nortwestern.edu <mailto:j-enterkin at nortwestern.edu>
>> Ph.D. Candidate
>> K.R. Poeppelmeier and L.D. Marks Groups
>> Department of Chemistry, Northwestern University
>> ------------------------------------------------------------------------
>>
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