[Wannier] Bands with "ripple"

[Eduardo Perassi]

Dear Robert,

                  Thanks for your e-mail !. I have calculated graphene bands with p2 orbitals in a supercell so i know that it is not so much computationally expensive. In this case i would need to use only the pz orbitals to reduce the tight binding hamiltonian so i would whish to improve the bands calculations  that correspond to the pz orbitals by means of some parameter of wannier90 or some calculation tecnich.
Thanks in advance, Eduardo.


________________________________
De: Robert Peyton Cline <Robert.Cline at colorado.edu>
Enviado: jueves, 26 de septiembre de 2019 16:14
Para: Eduardo Perassi <eduperassi at hotmail.com>
Cc: wannier at lists.quantum-espresso.org <wannier at lists.quantum-espresso.org>
Asunto: Re: [Wannier] (no subject)

Dear Eduardo,

In my experience when dealing with graphene, the wannierization works best when you include the sp2 orbitals with the pz orbitals.  This allows you to use a frozen window on all the states up to the Dirac point, and then your outer window can include any conduction bands that significantly contribute to the pi/pi* bands.  For a supercell like yours and on a remote computer cluster, this shouldn't be that computationally expensive.

Please refer to page 1430 in this paper<https://journals.aps.org/rmp/pdf/10.1103/RevModPhys.84.1419> (figure 6 and related text) for this procedure for a single cell of graphene.

Best,
Peyton Cline
5th Year PhD Student
Eaves Group
CU-Boulder

On Thu, Sep 26, 2019 at 1:09 PM Eduardo Perassi <eduperassi at hotmail.com<mailto:eduperassi at hotmail.com>> wrote:
Hi, I am using wannier90 to reproduce some bands of a big unit cell of graphene with 24 carbons atoms. I am using pz orbitals and I did not include sp2 orbitals so I am trying to reproduce only 24 bands. I attached to this email a picture of the bands. The image shows the bands which are affected by a "ripple" so, is it possible to remove the ripple by increasing the number of k point or any other parameter?  I will appreciate any help!, thanks.
Eduardo.
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