[Wien] core-hole calculation in a molecule

[Sam Trickey]

Good morning -
   Maybe I can give a little help.
   I never tried a core-electron binding energy.  Long ago, with the old 
Univ. Florida
APW (NOT LAPW!) code, Asok Ray, Joe Worth, and I did try the Slater 
transition state
for optical transitions in rare gas crystals.  We implemented it in a 
periodic way,
with half an electron moved above the Fermi level in each unit cell.  
That, in essence
is a Slater transition state treatment of an exciton.  It was all done 
in the context of
X-alpha but that is not a relevant restriction.  The citation is S.B. 
Trickey, A.K.
Ray, and J.P. Worth, Phys. Stat. Solidi (b) 106, 613 - 620 (1981).
   Peace, Sam



On 6/19/19 8:57 AM, Pavel Ondračka wrote:
> Dear Wien2k mailing list,
>
> I'm trying to calculate core electron binding energies using the
> Slaters transition state approach (half electron removed from the core
> compensated by the background charge) in an organic molecule.
>
> As part of the usual convergence checking I did four calculations with
> different amount of vacuum, with 5Å, 10Å, 15Å and 20Å in all directions
> in order to get some trend and try to extrapolate the final values.
> This is the approach similar to what I use for insulators (increasing
> supercell size), to estimate the supercell size error due to the
> Coulomb interaction between the periodic images of the charged atom.
> However to my first surprise there is no change in the binding energies
> (~0.01 eV) observed. Thinking about it more it makes sense though, as
> there is no screening in the vacuum, so there probably is no reduction
> of the interaction (like in the simple electrostatic example where the
> electric field intensity next to the infinite charged plane doesn't
> depend on the distance to it).
>
> I'm looking for an advice whether someone already tried something like
> this and if this kind of calculation (i.e., corehole for molecule,
> single atom, or even a 2D material) actually makes a sense from the
> physical point of view and also within the lapw framework... For now
> I'm comparing the relative shifts of the core electron binding energies
> of different carbon atoms within the molecule, and the results looks
> quite in agreement with the literature. However I'm not sure how much I
> can trust the results and if I can actually compare the values also
> with bulk materials.
>
> Any advice would be appreciated
> Best regards
> Pavel
>
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-- 
Samuel B. Trickey
QTP, Depts. of Physics and Chemistry
2324 Physics Building
Box 118435
Univ. of Florida
Gainesville, FL 32611-8435
Vox: 352-392-6978 (direct)
Vox: 352-392-1597 (receptionist)
Fax: 352-392-8722
http://www.qtp.ufl.edu/ofdft
http://users.clas.ufl.edu/trickey

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