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Is exchange parameter calculated from band energy Uele ?
Date: 2017/10/19 05:34
Name: Min Yi   <minyibhu@gmail.com>

Dear All,
I tried to calculate exchange parameter by jx in OPENMX.
The system is a tow-layer structure. Firstly, For the AFM state, I get total energy Utot(AFM) and band energy Uele(AFM). For FM state, I get Utot(FM) and Uele(FM). But I found that Uele(AFM)<Uele(FM), while Utot(AFM)>Utot(FM). It means that in terms of Utot, FM state is preferable, while in terms of Uele, AFM is preferable. It is very strange.
Then I used jx in OPENMX to calculate the interface Jij, which indicates AFM state is preferable. This agrees with the results from comparing Uele.
So my doubt is that: is the exchange parameter calculated from band energy Uele ?
Thanks in advance.

Best regards,
Min
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Re: Is exchange parameter calculated from band energy Uele ? ( No.1 )
Date: 2018/03/04 08:13
Name: T. Ozaki
References: t-ozaki@issp.u-tokyo.ac.jp

Hi,

In OpenMX the exchange coupling parameters are calculated using a magnetic force theorem
which is based on the second order perturbation theory for Uele not for Utot.
As for your reference, our recent study might be useful:
https://arxiv.org/abs/1710.07533

Regards,

TO
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