Wilson loop?

[Dominik Gresch]

Dear Young-Joon Song,

If Wien2k has an interface to Wannier90 already, implementing the 
interface to Wien2k should be pretty straightforward -- all that is 
needed is a function that creates the string which should be in the 
k-points file. This is described here: 
http://z2pack.ethz.ch/doc/2.0/tutorial_system.html#preparing-k-points-input

As a reference, the implementation of this function for the currently 
supported codes can be found here: 
https://github.com/Z2PackDev/Z2Pack/blob/master/2.0.x/z2pack/fp/kpoint.py 
If you have trouble creating this function, you could also send me an 
example how the k-point input should look.

For your second question, I'm not entirely sure if I understood 
correctly what you want to do. To get the Wilson loop just along a line, 
you can use the line calculation: 
http://z2pack.ethz.ch/doc/2.0/line.html#z2pack.line.run

The result of this calculation has an attribute 'wilson', which is the 
Wilson loop in the basis of the Wannier orbitals. Note that this 
attribute does not exist for the result of first-principles 
calculations. The problem with direct first-principles calculations is 
that the Wilson loop is generally given in a random basis, which makes 
it not very useful. Since keeping the overlaps in this case usually 
takes a lot of memory (and runtime for saving) we discard them in that 
case, but it would be possible to add a flag which enables keeping them.

Best regards,

Dominik Gresch


On 23.03.2017 15:09, Young-Joon Song wrote:
>
> Dear developers,
>
> Hello. I have learned about z2pack to calculate Z2 invariants and 
> Chern number.
>
> Unfortunately, I mainly use Wien2k code. Is there any plan to 
> implement fp-wien2k on z2pack?
>
> Anyway, I make a system using tbmodels with 'wannier90_hr.dat' file. ( 
> This file is from wien2wannier and Wannier90)
>
> model = tbmodels.Model.from_hr_file('wannier90_hr.dat')
> system = z2pack.tb.System(model, bands=6)
>
> Is it possible to calculate Wilson loop in this method?
>
> If so, can I use kpoints I made?
>
> This is because I want to calculate Wilson loop and  mirror Chern 
> numbers using kpoints along a line on a mirror plane of BZ.
>
> Any comments will be very helpful for me.
>
> Thanks in advance.
>
>
> Young-Joon Song
>

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