band structure for conventional cell  [SOLVED]

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shima123
Posts: 5
Joined: Tue Jun 11, 2019 12:25 pm

band structure for conventional cell

Post by shima123 » Tue Jul 09, 2019 10:37 am

Hi,
I am working on a crystal with r-3m structure (#166). Then, the conventional cell is hexagonal which its volume is three times bigger than primitive cell. i.e. r-3m.
There are some special high symmetry kpoints for r-3m structure.
I am going to plot band structure for conventinal cell, using these high symmetry kpoints of r-3m. Therefore, I need to know where the position of these points is in reciprocal space of hexagonal.

I'd appreciate if you could guide me how I can do that. Is there any post-processing for that in Abinit?

Thank you in advanced!

Best,
Shima

ebousquet
Posts: 469
Joined: Tue Apr 19, 2011 11:13 am
Location: University of Liege, Belgium

Re: band structure for conventional cell

Post by ebousquet » Fri Jul 12, 2019 4:08 pm

Dear Shima,
I guess you are asking for the label name and coordinate of k-points? This is something you can get from crystallography, for example the Bilbao server can give you that for each space group:
http://www.cryst.ehu.es/cryst/get_kvec.html
Best wishes,
Eric

shima123
Posts: 5
Joined: Tue Jun 11, 2019 12:25 pm

Re: band structure for conventional cell

Post by shima123 » Mon Jul 15, 2019 2:07 pm

Hi Eric,
Thank you for your reply.
That's true to some extent. However because of changing the brillouin zone of conventional cell, I guess there are some folding in the energy of different Kpoints, like some thing that we have about supercells. Then, we probably need to do unfolding process about that. I mostly meant that. Am I right?

Thank you so much!

regards,
Shima

ebousquet
Posts: 469
Joined: Tue Apr 19, 2011 11:13 am
Location: University of Liege, Belgium

Re: band structure for conventional cell  [SOLVED]

Post by ebousquet » Tue Jul 23, 2019 10:54 am

Dear Shima,
Yes, indeed, if you are using supercells then you have to do unfolding.
Linked to Abinit there is the program flod2bloch:
https://docs.abinit.org/guide/fold2bloch/
But I never used it, I cannot help you with this. The only limitation I know from this program is that it can unfold only "Cartesian" cell extension w.r.t. the unit cell orientation (I mean the supercell should not be rotated w.r.t. the unit cell).
Best wishes,
Eric

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