Determining the Magnetic Anisotropy
Description: Magnetocrystalline Anisotropy Energy determined non-self-consistently
The Magnetocrystalline Anisotropy Energy is determined by rotating all spins according to different directions. First of all, an accurate (PREC = Accurate, LREAL = .False.) collinear calculation (using the vasp-std script) in the ground state has to be done. Next, the Spin-Orbit Coupling (LSORBIT = .True. ; using the vasp-ncl script) is took into account non-self-consistently (ICHARG = 11) for several spin orientations. In most of cases, the changes in energies are very low (sometimes, it could be about the micro-eV). The number of bands has to be twice compared to a collinear run).
To modify the orientation of the spins in the crystal, we consider the second approach describes here. For the MAGMOM-tag, the total local magnetic moment is written according to the z direction (necessarily, the x and y-directions are equal to 0). The spin orientation [uvw] is defined by the SAXIS-tag in the Cartesian frame. The Magnetocrystalline Anisotropy Energy is calculated by orientating the spins in different directions and the following equation : EMAE = E[uvw] - Emin, with Emin the energy of the most stable spin orientation.
More details are available in the SAXIS and LSORBIT pages.
Exercise : Determine the Magnetocrystalline Anisotropy Energy of NiO in a non self-consistent approach by orientating the spins along the following path : (2,2,2) --> (2,2,1) --> (2,2,0) --> ... --> (2,2,-6). Compare to the self-consistent approach.
- INCAR
NiO MAE SYSTEM = "NiO" Electronic minimization PREC = Accurate ENCUT = 450 EDIFF = 1E-7 LORBIT = 11 LREAL = .False. ISYM = -1 NELMIN = 6 # ICHARG = 11 # LCHARG = .FALSE. # LWAVE = .FALSE. # NBANDS = 52 # GGA_COMPAT = .FALSE. DOS ISMEAR = -5 Magnetism ISPIN = 2 MAGMOM = 2.0 -2.0 2*0.0 # MAGMOM = 0 0 2 0 0 -2 6*0 # Including Spin-orbit # LSORBIT = .True. # SAXIS = 1 0 0 # Quantization axis used to rotate all spins in a direction defined in the (O,x,y,z) Cartesian frame Orbital mom. 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
- KPOINTS
k-points 0 gamma 4 4 4 0 0 0
- POSCAR
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
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