From the wien mailing list : [Wien] AFM NiO wrong magnetic moment

From the wien mailing list : [Wien] AFM NiO wrong magnetic moment

Marcus Ekholm Wed, 20 Nov 2013 05:11:55 -0800

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

 

NiO.struct

NiO                                                                            
R   LATTICE,NONEQUIV.ATOMS:  3                                                 
MODE OF CALC=RELA                                                              
  5.438490  5.43849026.6430489 90.000000 90.000000 90.000000                   
ATOM  -1: X=0.00000000 Y=0.00000000 Z=0.00000000
          MULT= 1          ISPLIT= 4
Ni1       NPT=  781  R0=0.00000500 RMT=    2.00     Z: 28.0                    
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM  -2: X=0.50000000 Y=0.50000000 Z=0.50000000
          MULT= 1          ISPLIT= 4
Ni2       NPT=  781  R0=0.00000500 RMT=    2.00     Z: 28.0                    
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM  -3: X=0.25000000 Y=0.25000000 Z=0.25000000
          MULT= 1          ISPLIT= 4
O         NPT=  781  R0=0.00000500 RMT=    1.73     Z:  8.0                    
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
   6      NUMBER OF SYMMETRY OPERATIONS
 0 0 1 0.00000000
 0 1 0 0.00000000
 1 0 0 0.00000000
       1
 0 1 0 0.00000000
 0 0 1 0.00000000
 1 0 0 0.00000000
       2
 0 0 1 0.00000000
 1 0 0 0.00000000
 0 1 0 0.00000000
       3
 0 1 0 0.00000000
 1 0 0 0.00000000
 0 0 1 0.00000000
       4
 1 0 0 0.00000000
 0 0 1 0.00000000
 0 1 0 0.00000000
       5
 1 0 0 0.00000000
 0 1 0 0.00000000
 0 0 1 0.00000000
       6

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