[Wien] hyperfine field calcaultion in the external magnetic field by ORB package

[Peter Blaha]

This option can be used for metals only.

The magnetic field has an influence on the spin (this is taken properly 
in the whole unit cell and usually is the dominant effect) and the 
orbital motion (this is calculate only approximative inside the sphere 
and for "good metals" is a small contribution).



On 08/19/2013 05:23 AM, Jing-Han Chen wrote:
> Dear WIEN2k users and authors
>
>    We are currently interested in hyperfine fields in an external
> magnetic field, and have a question about interpretation of the ORB
> package. We followed the Users Guide instructions in section 7.2 and
> section 4.5.6 (WIEN2k 13.1). For the case of s-hyperfine fields, we
> started with a simple test case of Al metal. As input, for interaction
> with Bext (nmod=3) and for lorb=0 we used the following
>
> -------------------top of file:
> case.inorb-------------------------------------------
> 3 1 0        nmod, natorb, ipr
> PRATT, 1.0    mixmod, amix
> 1 1 0        iatom nlorb, lorb
> 9.            Bext in T
> 0. 0. 1.    direction of Bext in terms of lattice vectors
> -------------------end of file:
> case.inorb-------------------------------------------
>
>    What was not clear to us was the statement in the first two lines
> manual page 101,  "orb calculates the orbital dependent potentials, i.e.
> potentials which are nonzero in the atomic spheres only and depend on
> the orbital state numbers l, m." Can anyone clarify whether the "spheres
> only" applies also to the applied magnetic field, or does the field
> apply also to the interstitial region?
>
>    In order to confirm our understanding, we tried two different RMT
> values as a comparison for fcc aluminum. The hyperfine field for 0%
> reduction (RMT=2.5) is 0.125 and that for 30% reduction (RMT=1.88) is
> 0.126. The calculation are initialized and calculated by the following
> command
>
> init_lapw -b -numk 5000 -red 0 -sp (and init_lapw -b -numk 5000 -red 30
> -sp, respectively)
> runsp_lapw -p -orb -cc 0.0000001
>
>    Interpreting these as s-contact hyperfine fields, the values seem
> entirely reasonable a compared to reported NMR shifts. Given the very
> large change in the volume of the spheres between calculations, we would
> have expected a much bigger difference if the applied field were
> confined only to the spheres, and our guess is that for this case, the
> field is applied uniformly to the interstitial region as well.
>
>    Any suggestion and comment are appreciated.
>
> --
> Jing-Han Chen
> Graduate Student
> Department of Physics
> Texas A&M University
> 4242 TAMU
> College Station TX  77843-4242
> jhchen at tamu.edu <mailto:jhchen at tamu.edu> <jhchen at tamu.edu
> <mailto:jhchen at tamu.edu>> / http://people.physics.tamu.edu/jhchen/
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>

-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WWW: 
http://info.tuwien.ac.at/theochem/
--------------------------------------------------------------------------