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MAGMOM-tag

MAGMOM= [real array]

Default:    
MAGMOM = NIONS*1.0 for ISPIN = 2
  = 3*NIONS*1.0 for non-collinear magnetic systems


Specifies the initial magnetic moment for each atom, if and only if ICHARG=2, or if the CHGCAR file contains no magnetisation density (ICHARG=1). If one is searching for a spin polarised (magnetic or antiferromagnetic) solution, it is usually safest to start from larger local magnetic moments, because in some cases, the default values might not be sufficiently big. A save default is usually the experimental magnetic moment multiplied by 1.2 or 1.5. It is important to emphasize that the MAGMOM tag is used only, if the CHGCAR file holds no information on the magnetisation density, and if the initial charge density is not calculated from the orbitals supplied in the WAVECAR file. This means that the MAGMOM tag is useful for two kind of calculations

Starting from VASP.4.4.4, VASP also determines whether the magnetic moments supplied in the MAGMOM line break the symmetry. If they do, the corresponding symmetry operations are removed and not applied during the symmetrization of charges and forces. This means that antiferromagnetic calculations can be performed by specifying anti-parallel magnetic moments for the atoms in the cell

 MAGMOM = 1 -1
As an example consider AF bcc Cr with the POSCAR file:
Cr: AF
 2.80000
  1.00000   .00000   .00000
   .00000  1.00000   .00000
   .00000   .00000  1.00000
  2
Kartesisch
   .00000   .00000   .00000
   .50000   .50000   .50000
With the MAGMOM line specified above, VASP should converge to the proper groundstate. In this example, the total net magnetisation is matter of factly zero, but it is possible to determine the local magnetic moments by using the RWIGS or LORBIT tags (see sections 6.34 6.33).


next up previous contents index
Next: ISTART-tag Up: The INCAR File Previous: ISPIN-tag   Contents   Index
N.B. Requests for support are to be addressed to: vasp.materialphysik@univie.ac.at