Usually, the magnetic moments of noncollinear tags in the INCAR file look like MAGMOM = 0.0 1.0 0.0 if the atom has 1 unit of the magnetic moment along the b axis. But if we consider the magnetic moments in ab plane of Double helical magnetic ordering, depends on the angle of the magnetic moments in atoms the MAGMOM tag will change. I don't know how it will change. Can anyone know how to give MAGMOM tag with respect to their magnetic moment angles?
In a non-collinear setup, the three MAGMOM values given to each atom are supposed to be the x, y and z-components of its magnetic moments which are not necessarily equal to the its crystalline a, b and c-components. For you case, you need to consider a supercell containing a sufficient number of atoms of the same type within the a-b plane to stabilize your desired helical spin ordering. You can then manually set the direction of magnetic moment (i.e tan(θ)=m_y/m_x, assume your a and b vectors are in x-y plane) on each atom using appropriate MOMGAM values m_x, m_y and (if necessary) m_z.
Thank you, sir. I have one more doubt. If I have CrAs which has the DHM ordering like the below picture. The angle between Cr1 and Cr2 is -120 degrees and Cr2 and Cr4 is 183 degrees. In this case how have to write MAGMOM tag in INCAR file.
You must create a large supercell containing as many Cr1 and Cr2 layers as needed to fulfil a full helical cycle. Starting from layer 1, you then set the corresponding MAGMON to [M 0 0] followed by [M*Cos(alpha_12), M*Sin(alpha_12), 0] for Cr2, [M*Cos(alpha_23-alpha_12), M*Sin(alpha_23-alpha_12), 0] for Cr3 and so on and so forth.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Atomic, Molecular and Optical Physics
- Atoms