Use of MAGMOM-tag

[edurgun]

Hi.
I have a question about the us of MAGMOM-tag. It is written in vasp-manual-4.6 that we need to enter the potential to the POTCAR twice for some AF calculations. And arrange the POSCAR as in below "trick".

POSCAR:
Cr: AF
2.80000
1.00000 .00000 .00000
.00000 1.00000 .00000
.00000 .00000 1.00000
1 1
Kartesisch
.00000 .00000 .00000
.50000 .50000 .50000

INCAR:
....
ISPIN=2
MAGMOM= 1 -1

>>> Suppose that I have 8 C atoms in my 2-D unit cell. And I want to impose initial magnetic moments on edge atoms. Should I try the
above trick ( enter 3 carbon potentials into one POTCAR, 3 kinds of atoms in POSCAR and MAGMOM= 2 4*0 -2) OR can I use MAGMOM= 2 0 0 0 0 0 0 -2 with only one carbon potential in POTCAR and only one kind of atom in POSCAR)

Are these two methods produce the same result ?

Thanks.

[admin]

the symmetry analysis as implemented in vasp.4.6 checks the orientation of the magnetic moments as well and should automatically find the spin-up and spin-down atoms as non-equivalent (please check in OUTCAR if the symmetry is reduced correctly). If this is the case, this 'trick' of defining the 3 atom types as non-equivalent explicitely need not be applied.
If the symmetry is NOT reduced automatically by the vasp version you use, please give the 3 C atoms as different atom types in POSCAR (1 4 1) and concatenate the C POTCAR 3 times.