[Wien] nonzero energy for zero-electron system

[Laurence Marks]

You have to remember that you are doing a charged cell calculation, so
you are in fact calculating the energy of a +1 charge in a smeared out
compensating -ve charge. In addition, with a LAPW calculation there
are some not so obvious additional corrections; if I remember
correctly you have to look at some of the papers by Art Freeman about
how the energy is calculated to work out what they are. Sorry, I did
look into this some years ago but have completely forgotten what the
corrections are so cannot help, but someone else might know specific
references.

N.B., the comment made earlier about the mixing is that you have to
ensure that you have the correct value for the 2nd parameter in the
first line of case.inm as otherwise the charge is going to be
renormalized to 1.

On Wed, Feb 10, 2010 at 12:39 PM, Yurko Natanzon
<yurko.natanzon at gmail.com> wrote:
> Further tests have shown, that changing the mixing method (e.g. MSEC
> to PRATT) as well as changing the mixing parameter results in slight
> changes in total energy, but it is still about -0.2 Ry.
>
> lstart doesn't really generate zero density, so I did it by hand
> setting all values of Clm coefficients in *clm* files to zero. That
> was my starting density which equals to the real one. then i did an
> "infinite" loop by running
>
> runsp_lapw -ec 0.0 -i 1000
>
> The result was that the final density remained zero, but the total
> energy remained -0.2 Ry. I understand, that this is a kind of
> implementation artefact which can't be avoided.
>
> My real question is whether this can somehow influence on the results
> of the following calculations:
>
> 1. the systems where the hydrogen has +1 charge (e.g. hydrogen fluoride, HF)
> 2. the systems where the hydrogen is H-, but one electron is removed
> and it becomes a proton (btw, is it possible to add or remove an
> electron from the particular atom?)
>
> --
> 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
> _______________________________________________
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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/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.