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

[Jing-Han Chen]

Dear Prof. Blaha,

  We appreciate the clarification on this. We thought by specifying only
the s orbital that we could limit things to the s-contact term but of
course it makes sense that at least the diamagnetic part is also included.
Apparently we must extract the spin polarization ourselves.
  However, as followup, we still don't clearly understand the limitations
of magnetic field application in the ORB package. For a solid with multiple
sites, if we specify only the atom of interest in the input file will the
situation correspond to a uniform field applied to all sites, or must we
list all sites in the input file?
  Note that as a test case we tried starting with our simple Al-metal
calculation, but we built the structure as if simple cubic with 4 sites,
and applied the field only to one site. This calculation will not converge
for us, from which we suppose that all sites need to be listed, is that the
case?


2013/8/19 Peter Blaha <pblaha at theochem.tuwien.ac.at>

> 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/<http://people.physics.tamu.edu/jhchen/>
>>
>>
>>
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>>
>>
> --
>
>                                       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/**
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-- 
Jing-Han Chen
Graduate Student
Department of Physics
Texas A&M University
4242 TAMU
College Station TX  77843-4242
jhchen at tamu.edu <jhchen at tamu.edu> / http://people.physics.tamu.edu/jhchen/
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