[Wien] Version 7.1 - Charged supercells

[Laurence Marks]

Essentially, the charged cell calculations in the earlier versions of
Wien were wrong, certainly for the energy and probably for the
electronic structure due to an inappropriate addition of charge
compensation. Peter corrected this, and I tested it in some detail.

There is still an energy correction which I am 98% confident is
-Q*V_0(Q)/2 where Q is the excess charge of the cell (-ve for a
negative cell) and V_0(Q) is the vacuum Coulomb potential in the
calculation which is a function of Q. I am reasonably confident that
this includes most additional correction terms that people have talked
about in the literature. The details of how I got this have not yet
been published, and might never be, but in principle could be posted
on the Wien page if there is an interest. This does require the user
to find, somehow, V_0(Q) which is not so easy.

On 1/29/07, E B Lombardi <lombaeb at science.unisa.ac.za> wrote:
> Dear Prof. Blaha
>
> I am interested to know more about the fixes for charged cells in lapw0:
>
> Specifically, whether the comments on the Wien list below still apply
> and whether the corrections for charged cells are included in this new
> version?
>
> What differences can be expected in old Wien2k06 vs new Wien2k07 charged
> supercell calculations?
>
> I assume the procedure outlined in the FAQ still applies unchanged?  It
> would also be useful to include charged supercell limitations/fixes in
> the FAQ.
>
> Thank you in advance
> Best regards
> Enrico Lombardi
>
> PS: the Wien2k usersguide available under "Textbooks" seems to be an
> older version than included in the SRC directory.  All versions of the
> guide state "November 2001" and "revised edition June 2002".
>
> >I would NOT trust these energies either!
> >There is no correction in E-tot for adding this background charge nor the
> >global correction for charged cells (described in literature).
> >
> >Use these charged cells only for "DOS" or core-level spectroscopy,...
> >
>
> >> I've always had some reservations about using the energy number that comes out
> >> of a charged cell calculation for anything. Since I did not find this
> >> discussed anywhere on the list, maybe someone can educate me as to whether it
> >> is useful (with perhaps some corrections) or to be avoided like the plague.
>
> >Does the energy that Wien2k gives for a charged cell require any
> >additional corrections beyond the standard ones in the literature,
> >e.g. Leslie and Gillan, J. Phys. C 18, 973 (1985)?
>
>
>
>
> Peter Blaha wrote:
> > Dear WIEN2k users,
> >
> > A new version, WIEN2k_07.1 is ready for download.
> >
> > Highlights:
> > batch-mode for init_lapw;
> > hybrid-methods for correlated electrons (may replace LDA+U)
> > SRC_lapw0: fixes for charged cells, electric field, speedup
> > SRC_lapwdm: more accurate orbital and dipolar hyperfine fields
> > SRC_lcore: increased precision in printout. Much more stable (in
> > particular for heavier elements), but may change :ENE in comparison to
> > previous versions
> >
> > Please see the update page of www.wien2k.at for details.
> >
> > Thanks to all contributions
> >
> > Best regards
> >
> > PS: Since a new year has started a reminder: Please submit your papers
> > where WIEN2k was used into our website at  http://www.wien2k.at/papers
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> >
> >
>
> --
> Dr E B Lombardi
> Physics Department
> University of South Africa
> P.O. Box 392
> UNISA 0003
> Pretoria
> South Africa
>
> Tel: +27 (0)12 429 8654 / 8027
> Fax: +27 (0)12 429 3643
> E-mail: lombaeb at science.unisa.ac.za
>
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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
http://www.numis.northwestern.edu