[QE-users] Query regarding k path selection, mismatching of band gap

[Poonam Kaushik]

Dear Expert,
About the first option, I used to confuse to select the correct option for
the occupation, smearing type, and broadening part. In my input file, I
used an 'mv' smearing with a broadening of 0.02 Ry. So either I can reduce
it to 0.01 Ry or  I can try any other occupation,  like tetrahedra or
fixed. my system is an insulator with a small bandgap of 0.04 eV. Also in
the third option, I calculated the k path by using the CIF file, and
k-pathfinder. Please correct me if I am wrong.

Thanks and regards,
Poonam Sharma




-------------------------------------------------------------------------------------------------
Poonam Sharma
Research Scholar
Department of Physics
Indian Institute of Technology Bombay
Mumbai - 400076
India.



On Wed, Oct 14, 2020 at 12:18 AM Nicola Marzari <nicola.marzari at epfl.ch>
wrote:

> On 13/10/2020 20:43, Poonam Kaushik wrote:
> > Dear Expert,
> > So the only option that I have is to include the complete path and do
> > the calculation again.
> > Thank you so much for your suggestion.
> >
>
> Mostly welcome, but you have three options - destiny can be generous
> sometimes.
>
> The first option would be doing a more careful DOS:
> https://www.quantum-espresso.org/Doc/INPUT_DOS.html
>
>                         nicola
>
> >
> >
> > Thanks and regards,
> > Poonam Sharma
> >
> >
> >
> >
> >
> -------------------------------------------------------------------------------------------------
> > Poonam Sharma
> > Research Scholar
> > Department of Physics
> > Indian Institute of Technology Bombay
> > Mumbai - 400076
> > India.
> >
> >
> >
> > On Tue, Oct 13, 2020 at 11:53 PM Nicola Marzari <nicola.marzari at epfl.ch
> > <mailto:nicola.marzari at epfl.ch>> wrote:
> >
> >
> >
> >
> >       From the most to the less likely, it could be that your DOS has
> some
> >     broadening that masks the existence of a small gap, or that the gap
> >     closes across the last two segments of the path that you are
> >     missing, or
> >     that you are very unlucky and the band gaps closes at points that do
> >     not
> >     lie on a high symmetry path.
> >
> >                   nicola
> >
> >
> >     On 13/10/2020 19:53, Poonam Kaushik wrote:
> >      >
> >      > Dear Experts,
> >      >   I have one query regarding k path selection. After using Kpath
> >     finder
> >      > (https://www.materialscloud.org/work/tools/seekpath ), i got
> >     this type
> >      > of  k path
> >      > G-M-K-G-A-L-H-A|L-M|H-K for my structure. In the calculation, I
> >     used, up
> >      > to G-M-K-G-A-L-H-A. So, is this ok to select a path up to this?
> >      > Basically in the band structure, I am getting some finite gap
> >     while in
> >      > dos I m getting a zero bandgap, after selecting the path up to
> >      > G-M-K-G-A-L-H-A. I am not able to figure out why this is
> happening?
> >      > Should it help to include the complete path? I am attaching here
> my
> >      > input file, band structure, and dos. Please have a look.
> >      >
> >      >
> >
> https://drive.google.com/drive/folders/1UhUgod8KnvdovJfxMqbJMQwdtb3dE-yY
> >      >
> >      >   I'll be very thankful for any suggestions.
> >      >
> >      > Thanks and regards,
> >      > Poonam Sharma
> >      >
> >      >
> >      >
> >      >
> >
>  -------------------------------------------------------------------------------------------------
> >      > Poonam Sharma
> >      > Research Scholar
> >      > Department of Physics
> >      > Indian Institute of Technology Bombay
> >      > Mumbai - 400076
> >      > India.
> >      >
> >      >
> >      > _______________________________________________
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> >      >
> >
> >
> >     --
> >
>  ----------------------------------------------------------------------
> >     Prof Nicola Marzari, Chair of Theory and Simulation of Materials,
> EPFL
> >     Director, National Centre for Competence in Research NCCR MARVEL,
> EPFL
> >     http://theossrv1.epfl.ch/Main/Contact
> http://nccr-marvel.ch/en/project
> >
>
>
> --
> ----------------------------------------------------------------------
> Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
> Director, National Centre for Competence in Research NCCR MARVEL, EPFL
> http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project
>
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