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

[Jing-Han Chen]

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 <jhchen at tamu.edu> / http://people.physics.tamu.edu/jhchen/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20130818/66ed2b46/attachment.htm>