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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