[QE-users] magnetic structure has larger periodicity than crystal structure

[Abdesalem Houari]

Hello,
I strongly believe that the super-cell approach is the only method for this kind of situations; not only in QE, but in all DFT codes using Bloch theorem and cristalline symmetry. 

For me, I'd never encountered another way to do that.  

Best regards

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Dr. Abdesalem HOUARI-------------------------------------------------------------------------------------------
Department of physics, Theoretical Physics Laboratory
University of Bejaia-06000. Algeria.
E-mail: abdeslam.houari at univ-bejaia.dz & habdslam at yahoo.fr
https://sites.google.com/site/houariabdeslam/homepage
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    On Wednesday, 30 October 2024 at 11:09:39 pm GMT+1, Johnson, Miles R. <mjohnso7 at caltech.edu> wrote:  
 
  Hello,
There exist materials where the magnetic unit cell is larger than the primitive crystal unit cell. For instance, in FePS3, the primitive crystal unit cell has two Fe atoms, just like graphene. However, the material is zig-zag antiferromagnetic, and also its spins flip between layers, so to describe the crystal structure including details about the magnetic structure one must include 8 Fe atoms.

I'm fairly certain the only way to deal with this situation in quantum espresso is to use a supercell which includes all 8 Fe atoms necessary to describe the magnetic structure, but I'm curious if anyone else has found other solutions. FePS3 already has a fairly large unit cell, so the computations become expensive quickly when you use a supercell 4 times as large.
Best,Miles

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