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<p>Dear PWscf community,<br>
<br>
I am wondering whether one can perform calculations with PWscf<br>
using the virtual crystal approximation (VCA) for systems, where one<br>
site is only partially (10-30%) occupied by a magnetic atom, and the rest of<br>
the site is empty?<br>
<br>
I am interested in using VCA in combination with LDA+U or PBE+U, because<br>
I have to study a large system which does not work with full-electron codes<br>
where one can take advantage of the coherent potential approximation (CPA).<br>
<br>
By browsing through the mailing list, as I understood, in PWscf <br>
such VCA calculations can be performed by generating first a new "mixed" type<br>
pseudopotential with the virtual.x utility. I can imagine how that would work, <br>
if I have a system where as an example one has a mixture of 50% Fe <br>
and 50% Co or something similar on an atomic site.<br>
However, how is one supposed to proceed, if a site is only partially occupied,<br>
and the rest of the site is empty?<br>
Can one even generate such thing as a completely empty potential, which than<br>
need to be mixed with the real potential of the particular atoms (Fe and Co in my case)?<br>
If yes, would that still work with VCA, and would the results be trustworthy?</p>
<p><br>
<br>
Any helpful remark/comment is appreciated.<br>
<br>
Best regards,<br>
Janos.<br>
</p>
<p><br>
</p>
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<div style="font-family:Tahoma; font-size:13px">==========================================<br>
Dr. Janos Kiss e-mail: kissi@uni-mainz.de<br>
Johannes Gutenberg-Universitaet<br>
Institut f. Anorg. u. Analyt. Chemie<br>
AK Prof. Dr. Claudia Felser<br>
Staudinger Weg 9 / Raum 01-230<br>
55128 Mainz/ Germany<br>
Phone: +49-(0)6131-39-22703<br>
Fax: +49-(0)6131-39-26267<br>
Web: http://www.superconductivity.de/<br>
=========================================
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