[Wannier] Postw90 and Berry curvature origin

[Vahid Askarpour]

Dear Professor Vanderbilt,

Thank you for taking the time to respond to my question. I did not realize that this question is so involved. Seems like I have a lot of reading to do.

Best,
Vahid

> On Jan 6, 2024, at 4:01 PM, David Vanderbilt <dhv at physics.rutgers.edu> wrote:
> 
> CAUTION: The Sender of this email is not from within Dalhousie.
> 
> Vahid,
> 
> The details are probably complicated, but probably the short answer
> is that Fe is a centrosymmetric collinear magnet.  In this case
> the Berry curvature vanishes everywhere in the BZ in the absence
> of SOC.  Roughly, the SOC goes like L.S which does have an (Lz Sz)
> spin-diagonal component, but typically the (L+ S-) and (L- S+)
> spin-mixing terms are more active.
> 
> I hope this helps a little...
> 
> David
> 
> 
> On Wed, 3 Jan 2024, Vahid Askarpour wrote:
> 
>> Dear Wannier90 Users,
>> 
>> Looking at the postw90 background paper (PRB74, 195118, 2006), in Fig. 3a, there is a large spike and several small spikes for the Berry curvature in Fe. The large peak is attributed to spin-orbit coupling with states above and below E_F. However, both small and large peaks produce small energy denominators in Eq. 31. This might be obvious to many but  why is the peak due to spin-orbit much larger than the other peaks?
>> 
>> Thanks,
>> Vahid
>> 
>> Vahid Askarpour
>> Department of Physics and Atmospheric Science
>> Dalhousie University,
>> Halifax, NS
>> CANADA
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> 
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