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# Constraining the local magnetic moments

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Description: Constraining the local magnetic moments on NiO.

To orientate locally each spin, a penalty energy Ep is added, inversely proportional to the LAMBDA parameter. Thus, the process has to begin with a low LAMBDA, which is increased step by step.

For additional informations, go to the I_CONSTRAINED_M page.

Exercise : Verify the Ep=f(1/LAMBDA) relation by constraining the spin directions. Check the efficiency of the method by constraining only the direction, then the direction and the size of spins.

```NiO GGA+U Constr.
SYSTEM        = "NiO"

Electronic minimization
ENCUT         = 450
EDIFF         = 1E-5
LORBIT        = 11
LREAL         = .False.
ISYM          = -1
NELMIN        = 6
LSORBIT       = .True.
GGA_COMPAT    = .FALSE.

DOS
ISMEAR    = -5

Magnetism
ISPIN     = 2
I_CONSTRAINED_M = 1  # direction
# I_CONSTRAINED_M = 2  # size and direction
M_CONSTR  = 2 0 0 0 -2 0 6*0
LAMBDA    = 1
RWIGS     = 1.30 0.70

Orbital moment
LORBMOM  = T

Mixer
AMIX      = 0.2
BMIX      = 0.00001
AMIX_MAG  = 0.8
BMIX_MAG  = 0.00001

GGA+U
LDAU      = .TRUE.
LDAUTYPE  = 2
LDAUL     = 2 -1
LDAUU     = 5.00 0.00
LDAUJ     = 0.00 0.00
LDAUPRINT = 2
LMAXMIX   = 4

```
```k-points
0
gamma
4  4  4
0  0  0
```
```NiO
4.17
1.0 0.5 0.5
0.5 1.0 0.5
0.5 0.5 1.0
2 2
Cartesian
0.0 0.0 0.0
1.0 1.0 1.0
0.5 0.5 0.5
1.5 1.5 1.5
```