It seems the hexagonal structure is from a 1962 publication (some journal where 
I do not have acceess)
there is a much more recent determination from 1999 (ZAAC 625 page 2050) by Ruck
that tells it is a much more complicated structure in space group F 1 2/m 1 
(no. 12)
the XRD pattern for both structures shown in Pearsons Handbook are very 
similar, therfore one may assume that the hexagonal structure might not be the 
correct one

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von pieper 
[pie...@ifp.tuwien.ac.at]
Gesendet: Dienstag, 10. November 2015 11:25
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] large deviation of atomic volume in BiNi compound

Since you ask for ideas and without really looking at the problem:
Assuming that the experimental numbers are correct, is this a room
temperature structure? The calculations are, of course, ground state
zero Kelvin, so things might go south if there is a phase transition
somewhere. Considering the elements you deal with maybe magnetic? What
are the forces in your calculations?

Good luck,

Martin


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 10.11.2015 10:21, schrieb Tomas Kana:
> Dear Wien2k users,
>
> I came across a problem with equilibrium atomic volume of
>
> the BiNi compound. The experimental lattice is hexagonal
>
> with a = 4.079 Angstroem, c = 5.359 Angstroem
>
> (P. Villars, Pearson's Handbook: Crystallographic Data for
> Intermetallic Phases)
>
> However, the equilibrium volume turns out to be more
>
> than 16 % higher than the experimental one.
>
> I wonder since the equilibrium volume of
>
> pure Bi and Bi3Ni comes out with much better agreement with
>
> experiment (about 4 to 5 % deviation).
> I used GGA (no spin orbit coupling),
>
> Rmt*Kmax = 8.8, lmax = 10, Gmax = 16, 5000 k-points in the
>
> whole Brillouin zone. I enclosethe structure file in attachment.
>
> I tried LDA that gives better agreement with experiment
>
> (about 10 % deviation) but I think this is still too much. I have
> tried
>
> to use gaussian smearing instead of the tetrahedron method,
> increase Rmt*Kmax to 11, increase k-points to 20 000 in the whole
> Brillouin zone but nothing helped.
> In the mailing list I found someone had similar problem with a more
> complicated structure containing bismuth, but that was not solved:
> http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg10479.html
> Do you have any idea?
> Thank you in advance
> With best regards
> Tomas Kana
> Institute of Physics of Materials,
> Academy of Sciences of the Czech Republic
> Brno, Czech Republic
>
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