[Wien] Bad formation energies for the charged vacancies

[Yurko Natanzon]

Thank you for the answers. The problem now becomes more clear to me.

> The question is then how to do a realistic charged cell calculation
> with meaningful energies taking account of the effect of a potential
> shift? If vacuum is available one can determine the potential shift
> and correct; one can also calibrate the value of a core level and use
> this to determine the shift (with reservations) but it would be nice
> to have a more elegant method......

I have actually tried to do this with Mg 2p electrons of MgH2, but
with no success. For the neutral cell we have one localized peak
centered at approximately -42.5 eV below the Fermi level, and when we
add a charge the peak delocalizes and is splitted into two smaller
peaks due to the Stark effect. And yes, it is shifted to about +/- 2
eV depending on the charge sign, but I don't know how to measure a
shift in this case. But suppose we just take the center of the further
located peak and it will give the largest possible value of the shift,
this will not improve the results significantly... i didn't check it
for the deeper 1s states, but it should give the similar results.

-- 
Yurko (aka Yuriy, Iurii, Jurij etc) Natanzon
PhD student
Department for Structural Research (NZ31)
Henryk Niewodniczański Institute of Nuclear Physics
Polish Academy of Sciences
ul. Radzikowskiego 152,
31-342 Krakow, Poland
E-mail: Yurii.Natanzon at ifj.edu.pl, yurko.natanzon at gmail.com