[Wien] Help on AFM Structure

[Chinedu Ekuma]

Hi Rocqueflte,
The experimental magnetic structure is not known. What I wanted to do is to study it in terms of the various AFM structures. However, as I explained before, constructing the various AFM orders is confusing. For example, the Collinear AF, Bicollinear AF, Neel AF, A-type, etc. If you can explain to me how I can achieve this using the structure I attached before, it will be appreciated.

From your earlier response, "Do I repeat the up and down spins for all the Fe to get the CAF?

Once again, thanks for your assistance so far.

 

C.  Ekuma

                                   
 
 
 



On Sunday, January 19, 2014 11:23 AM, Rocquefelte <xavier.rocquefelte at cnrs-imn.fr> wrote:
 
If you know the experimental magnetic structure, then you must specify the spin state of each iron atoms in accordance. 
If you don't know the experimental ground state magnetic
      structure, you will need to try a series of magnetic orderings. 
In the second case, it must be done with care (same cell and space
      group) because the energy differences between two magnetic states
      can be quite small (few meV). 

Cheers

Xavier


Le 1/19/2014 2:25 PM, Chinedu Ekuma a écrit :

Hi Rocqueflte,
>Thank you very much for your explanations. Do I repeat it all through in pairs as you showed or just for the Fe1 and Fe2?. My concerns was that due to the structure, I couldn't identify a plane for the AFM. Assuming up is u and down is d, do I just do: ududududud... for the whole Fe in the structure? If this is the case, how then do one differentiate this from other AFM configurations like A-type or bicollinear?
>
>
>
>Once again, thank you for your time and explanations.
>
>
>  
>C.  Ekuma
>
>                                   
> 
> 
> 
>
>
>
>On Sunday, January 19, 2014 2:07 AM, Rocquefelte <xavier.rocquefelte at cnrs-imn.fr> wrote:
> 
>Here is one way to do it. 
>Keep the P1 symmetry (if really needed for the AFM
                      collinear magnetic order you need). 
>Generate the file case.inst (input file of lstart
                      created after symmetry). 
>Here I provide the beginning of this file. You can
                      see the electronic configuration of Fe1 and Fe2. 
>Imagine that in your collinear magnetic phase Fe1
                      and Fe2 are respectively up and down. 
>Thus you must change the case.inst file in the
                      following manner. 
>
>Fe
>Ar 3
>3, 2,2.0  N 
>3, 2,2.0  N
>3,-3,2.5  N
>3,-3,0.0  N
>4,-1,1.0  N
>4,-1,0.5  N
>Fe
>Ar 3
>3, 2,2.0  N
>3, 2,2.0  N
>3,-3,0.0  N
>3,-3,2.5  N
>4,-1,1.0  N
>4,-1,0.5  N
>
>For Ga atoms, if they are non-magnetic (or not
                      far) the best is to start with a non-magnetic
                      atomic configuration as below:
>
>Ga
>Ar 4
>3, 2,2.0  N
>3, 2,2.0  N
>3,-3,3.0  N
>3,-3,3.0  N
>4,-1,1.0  N
>4,-1,1.0  N
>4, 1,0.5  N
>4, 1,0.5  N
>
>Then you must run "x lstart", and continue
                      initialization "x dstart -up / x dstart -dn" ...
                      It will generate the proper collinear magnetic
                      order ... 
>At this stage you don't need to use the option
                      "run_afm" ... this option is needed only if you
                      cannot keep the magnetic order you have previously
                      defined. 
>
>More details are available in the userguide and
                      here: 
>
>http://www.wien2k.at/reg_user/faq/afm.html
>
>www.wien2k.at/reg_user/textbooks/WIEN2k_lecture-notes_2013/magnetism.pdf
>
>http://www.wien2k.at/reg_user/textbooks/WIEN2k_lecture-notes_2013/Relativity-NCM.pdf
>
>Best Regards
>
>Xavier
>
>
>
>
>
>
>Le 1/19/2014 1:41 AM, Chinedu Ekuma a écrit :
>
>Dear All,
>>I am trying to construct a collinear AFM
                          structure from the attached file. Please, any
                          help will be greatly appreciated.
>>
>>
>>
>> Thanks.
>>C.  Ekuma
>>
>> 
>> 
>>
>>
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