[Wien] Are fractionally charged atoms possible in Wien2k?

[Stefaan Cottenier]

What you are doing is identical to the 'virtual crystal approximation' 
-- search the wien2k mailing list archive for this. Shortly said: do a 
normal initialization first, and only afterwards change Z in case.struct 
and case.in2 (not in case.inst). As far as I remember, this can be done 
with 1 digit precision only (x.2, x.3, but not x.25).

Stefaan

Oleg Rubel wrote:
> Dear Wien2k Users,
>
> in calculations of polar semiconductor surfaces, I came to the point where 
> I need to introduce fractionally charged hydrogen atoms in order to 
> passivate an irrelevant side of the slab. The fractionally charged atom 
> means an atom with a non-integer nuclear charge and the corresponding 
> non-integer number of electrons, i.e., 1.25 or 0.75 in the case of 
> fractionally charged hydrogen atoms.
>
> My first attempt with WIEN2k_08.1 (Release 14/12/2007) was not successful. 
> I edited the structure file using w2web and put Z=0.75 instead of default 
> 1.0 for hydrogen. In the structure file, I have got 0.8 instead of 0.75, 
> which is a fault of w2web because Z has F5.2 format. Of course it is not 
> what I want, but I decided to stay with 0.8 and continue further. Real 
> problems begin with LSTART. I edited the case.inst file in order to bring 
> the number of electrons in agreement with the nuclear charge Z=0.8. The 
> corresponding part of case.inst is shown below:
>
> H 1
> 1
> 1,-1,0.7  N
> 1,-1,0.1  N
>
> LSTART stops on 1S orbital of the pseudohydrogen and generates the 
> following error message:
>
> ERROR !!! nstop,iter,tets,test 28 1 9.999999939225290E-009
>
> If I put the hydrogen charge back to Z=1 and correspondingly change the 
> case.inst file, LSTART runs error free.
>
>
> Any ideas?
>
>
> Thank you in advance,
>
> Oleg Rubel
>
> ===========================
> Oleg Rubel, Ph.D.
> Faculty of Physics
> Philipps University Marburg
> Renthof 5, 35032 Marburg, Germany
> E-mail: Oleg.Rubel at physik.uni-marburg.de
> Homepage: http://www.staff.uni-marburg.de/~rubel/
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