Re: Question Regarding Small Exchange Constants from TB2J

[Xu He]

Hello,

- The SrMnO3 results looks fine to me. I don't see why the Tc goes to 0 in this case. How do you check the Tc? Do you use something like specific heat, or magnetic susceptibility? 

- The Cr2SeO result is very strange. While this system has a four-fold rotation symmetry, but the exchange parameters doesn't seem to be symmetric.

Could you try setting the translate_home_cell to false. Sometimes this causes trouble. 

Best regards, 

HeXu

On Sat, Nov 22, 2025 at 1:46 PM Jieun Kim <jieu...@gmail.com> wrote:

Dear TB2J developers,

I hope this message finds you well. I am a master's student currently using TB2J to generate UCF files for subsequent Vampire simulations.

While reproducing the Neel temperature of a Cr2SeO system (VASP -> Wannier90 -> TB2J), I am consistently encountering an issue where the exchange constants obtained from TB2J appear to be very small.
As a result, Vampire simulations give Neel temperatures close to 0 K.
The same issue occurs even when I use the latest TB2J version (0.9.12.17) and when I test the example systems provide in the TB2J package (e.g., SrMnO3)

I am wondering whether I may be missing something in the workflow or misusing the code.
I have attached the Wannier90 outputs and UCF files for both Cr2SeO and the SrMnO3 example.

I would sincerely appreciate any guidance or advice you could provide.

Thank you very much for your time.

Best regards,
Jieun Kim

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