[Wien] AFM NiO wrong magnetic moment
Marcus Ekholm
marekh at ifm.liu.se
Wed Nov 20 14:10:35 CET 2013
Dear Wien2k experts,
I use Wien2k 13.1. I am trying some basic LSDA/GGA (not +U) calculations
for (111)-layered AFM NiO with the setup as suggested in the exercises
below:
http://www.wien2k.at/events/ws2008/talks/Exercises_08.pdf
However, I find that although it reaches an AFM solution, the local
magnetic moment at fixed volume is much too small compared to previous
LSDA/GGA calculations (e.g. Tran, Blaha, et al, Phys. Rev. B 74:155108). In
addition, relaxing the volume I find it to collapse to a much too small
volume and consequently a very small magnetic moment.
More specifically:
With plain PBE-GGA I get the local spin moment 1.1 bohr magnetons as
compared to 1.4. This is at the GGA (cubic) lattice constant 4.2 Å
corresponding to the hexagonal lattice constants a=5.61220 and c=27.49406
a.u.. With LSDA I get 0.9. I've tried increase the number of k-points,
rkmax etc, but this doesn't seem to be the problem. Relaxing the volume
with LSDA I get a=5.15171 and c=25.23811 a.u. corresponding to a=3.86 Å,
and with the magnetic moment 0.6 bohr magnetons. In the reference above you
got 4.07 Å and 1.2 bohr magnetons.
I use the attached struct file and initalize calculations with
init -b -sp -vxc 5 -numk 10000 -rkmax 9.0 -ecut -9.0
having switched up/down for Ni1 and Ni2 in the inst file, and I make O
nonmagnetic. I start it with runsp_lapw and I get no warnings or
convergence problems down to 1 microRy.
So I believe there must be something wrong with my struct file.
Could you please check if you see anything weird?
Best regards,
Marcus Ekholm
Linköping University
Sweden
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