# [Wien] DOS for FSM calc - problem

Fecher, Gerhard fecher at uni-mainz.de
Fri Oct 11 12:44:42 CEST 2013

If you like to have a correct density of states and a magnetic moment of 6 muB as found in the experiment for Co2FeSi
then you may better use one of the hybrid functionals e.g. PBE0

What is the meaning of two different Fermi energies ?
I know that there was a paper published about Co2FeSi where FSM was used,
but finally it is seen (fig 6 of that paper) that the density of states calculated by use of FSM is nonsense,
as the low lying a1 band exhibits a very large exchange splitting (more then 1 eV)
that is not physical for s states.
Overall the FSM just shifts the energy scales of the majority and minority densities away from each other
(to have more majority and less minority states) until the 6 muB are reached, but that does not have a physical reality.

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
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at]&quot; im Auftrag von &quot;Dominik Legut [dominik.legut at vsb.cz]
Gesendet: Freitag, 11. Oktober 2013 08:19
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] DOS for FSM calc - problem

point a) was clear to me already before.

point b) was new.

Now, it it clear.  I want to have a correct DOS w.r.t. Fermi level. for up and
dn channel. Hence I rewrote manually Fermi energy for up and
dn channel in case.qtlup case.qtldn (after calling x lapw2 -qtl -up/dn)

It seems that this trick works as I can see that tetra on line 218 is reading
EFERM from case.qtlup/case.qtldn file.

Hopefully this is what you meant by "introducing two Fermi energies".

Best regards,

Dominik Legut

>Dne čtvrtek 10 října 2013 09:18:11 jste napsal(a): > Two remarks to the
problems reported below:
>
> a) After a runfsm calculation, you do NOT have valid case.vectorup/dn
> files (only dn), so you cannot calculate QTLs directly, but need to
> recalculate   x lapw1 -up
>
> b) Of course, in many cases a FSM calculation will give you the desired
> moment ONLY by introducing 2 different FERMI energies !.
> This is not considered when you calculate the QTLs and thus the
> automatic EF-settings in tetra will not be correct!
>
>
>
>
>
> ----------------------------------------------------------------
> I have a trouble to calculate the DOS for FSM calculation. I have
> converged FSM=6.0\mu_B for GGA(PBE) of Co2FeSi using Wien2k 12.1. At the
> end I checked grep :MMTOT and had a 6\mu_B/unit cell. However, where I
> make a plot according to UG about FSM I am getting a DOS that is similar
> to that of pure GGA (i.e. M=5.56\mu_B). Difference of integr. of up and
> down channels gives me 5.56 like in GGA.
>
> Where I could make a step aside?
>
> Can someone help to identify it?
>
> I am attaching a converged calculation, with *.int and outputting
> *.dos1ev*.
>
> Thanks,
>
> Best regards,
>
> Dominik Legut
>
> -------------------------------------------------
>
> Dominik Legut, tel. +420-597 329 122
>
> Nanotechnology Centre and IT4Innovations
>
> VSB University of Technology Ostrava
>
>
> CZ-70833 Ostrava
>
> Czech Republic
>
> -------------------------------------------------
--
S pozdravem

Dominik Legut

-------------------------------------------------
Dominik Legut, tel. +420-597 329 122
Nanotechnology Centre and IT4Innovations
VSB University of Technology Ostrava