I don't know what your question is, but hope that a comment might help.

Apparently you did not change size and shape of the unit cell (using a 1*1*1 supercell), so the lattice constants and angles are the same. However, you told sgroup that there is not one type of Ni in the unit cell but two. This change in the decoration of the bricks your crystal is built of broke some symmetries in their arrangement - now you are down to monoclinic.

I don't know exactly what af wave vector you want to establish in your structure (+-+-, or ++--++--, or ... counting along which direction?). Is your problem that your Ni1 and Ni2 are not the two you actually wanted to have antiparallel moments?

If 'afIII' fits into this unit cell (Ni1 and Ni2 do have antiparallel moments), and if the atoms are where you want them, run symmetry, set spin directions in case.inst, run lstart ...

Type III sounds comlicated enough to not fit into this unit cell - meaning that you cannot complete one period of the +/- count in your chosen direction within the unit cell. In that case you have to change shape and/or size of the unit cell. Maybe the options provided by supercell (double the cell along basis directions ...) are sufficient. There is no guarantee for this to be the case. You may have to work out the fitting new shape and the positions of the atoms in the new unit cell using additional tools.

I hope this helps,

Martin Pieper


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 22.10.2017 20:57, schrieb Abderrahmane Reggad:
Dear wien users

I am studing the magnetic structure of type III for a orthorhombic
structure.

After doing the supercell and labelling the independent atoms for
spin-up and spin-dn atoms and using the sgroup command I got the
following structure:

The space group of a monoclinic structure and the lattice parameters
are those of orthorhombic structure.

NiS-MnP-afmIII

P   LATTICE,NONEQUIV.ATOMS:  4 11_P21/m

MODE OF CALC=RELA unit=bohr

 10.998349 10.005529  6.864228 90.000000 90.000000 90.000000

ATOM  -1: X=0.25021227 Y=0.99991424 Z=0.25000000
          MULT= 2          ISPLIT= 8
      -1: X=0.74978773 Y=0.00008576 Z=0.75000000
Ni1        NPT=  781  R0=0.00005000 RMT= 2.21        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=0.75024661 Y=0.50012576 Z=0.75000000
          MULT= 2          ISPLIT= 8
      -2: X=0.24975339 Y=0.49987424 Z=0.25000000
Ni2        NPT=  781  R0=0.00005000 RMT= 2.21        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=0.08986359 Y=0.75012482 Z=0.75000000
          MULT= 2          ISPLIT= 8
      -3: X=0.91013641 Y=0.24987518 Z=0.25000000
S 1        NPT=  781  R0=0.00010000 RMT= 1.81        Z: 16.0

LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM  -4: X=0.41013993 Y=0.25012471 Z=0.75000000
          MULT= 2          ISPLIT= 8
      -4: X=0.58986007 Y=0.74987529 Z=0.25000000
S 2        NPT=  781  R0=0.00010000 RMT= 1.81        Z: 16.0

LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
   4      NUMBER OF SYMMETRY OPERATIONS

Best regards
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