[Wien] Calculating XPS spectra in Wien2k

[Laurence Marks]

EF of E_vacuum for the comparison?

On Wed, Sep 17, 2008 at 12:58 AM, Peter Blaha
<pblaha at theochem.tuwien.ac.at> wrote:
> 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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>>> Wien mailing list
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>>>
>>
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-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/IUCR_CED