[Pw_forum] supercell band structure

ashkan shekaari shekaari at gmail.com
Thu May 18 08:33:28 CEST 2017 

You should take band unfolding into consideration. For example, for a unit
cell if we have
Kpoints
x      y      z      n
...

for a 2×2 super cell we should write
Kpoints
2x     2y      2z      n

2×2 Super cell ----> bz is multiplied by 1/2 ----> kpoints must be
multiplied by 2 to neutralize such a change.

On May 18, 2017 1:45 AM, "Pietro Bonfa'" <pietro.bonfa at fis.unipr.it> wrote:

> Dear Mohammadreza Hosseini,
>
> are you talking about band folding? I wrote a small utility to unfold
> the band structure of supercells long time ago. It's in a git repository
> hosted on qe-forge.org (project name is unfold).
>
> Kind regards,
> Pietro Bonfa'
>
> On 05/15/2017 11:16 AM, Mohammadreza Hosseini wrote:
> >
> >
> > ________________________________________
> > From: Mohammadreza Hosseini
> > Sent: Sunday, May 14, 2017 1:43 AM
> > To: pw_forum at pwscf.org
> > Subject: Re: Pw_forum Digest, Vol 118, Issue 12
> >
> > Dear All
> >
> > I am calculating the band structure of phagraphyne. First we computed
> for primitive unit cell and then for the 2X2 supercell. Although the bulk
> structure is same the band structure is different. What is the problem ?
> Should parameters be optimized again for supercell?
> >
> > Mohammadreza Hosseini
> > Tarbiat modares uiversity
> > ________________________________________
> > From: pw_forum-bounces at pwscf.org <pw_forum-bounces at pwscf.org> on behalf
> of pw_forum-request at pwscf.org <pw_forum-request at pwscf.org>
> > Sent: Saturday, May 13, 2017 10:00 PM
> > To: pw_forum at pwscf.org
> > Subject: Pw_forum Digest, Vol 118, Issue 12
> >
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> > Today's Topics:
> >
> >    1. Re: how to determine the symmetry of a given phonon mode  in
> >       quantum espresso (Lorenzo Paulatto)
> >    2. Re: Gipaw - Magnetic susceptibility (Davide Ceresoli)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Sat, 13 May 2017 15:08:04 +0200
> > From: Lorenzo Paulatto <lorenzo.paulatto at impmc.upmc.fr>
> > Subject: Re: [Pw_forum] how to determine the symmetry of a given
> >         phonon mode     in quantum espresso
> > To: PWSCF Forum <pw_forum at pwscf.org>
> > Message-ID: <1728518.gkaUiGcZ5e at paulaxps>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > On Friday, 12 May 2017 23:44:33 CEST Mihiri Hewa bosthanthirige wrote:
> >> Hi,
> >> I am graduate student at Clemson university, currently working with
> Quantum
> >> Espresso. I would like to know how to determine the symmetry of a given
> >> phonon mode in quantum espresso.
> >
> > Hello,
> > it is printed in the output of phonon at the end of the calculation,
> i.e.:
> > ...
> >     End of self-consistent calculation
> >
> >
> > --
> > Dr. Lorenzo Paulatto
> > IdR @ IMPMC -- CNRS & Universit? Paris 6
> > +33 (0)1 44 275 084 / skype: paulatz
> > http://www.impmc.upmc.fr/~paulatto/
> > 23-24/4?16 Bo?te courrier 115,
> > 4 place Jussieu 75252 Paris C?dex 05
> > -------------- next part --------------
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> >
> > ------------------------------
> >
> > Message: 2
> > Date: Sat, 13 May 2017 16:09:02 +0200
> > From: Davide Ceresoli <davide.ceresoli at cnr.it>
> > Subject: Re: [Pw_forum] Gipaw - Magnetic susceptibility
> > To: PWSCF Forum <pw_forum at pwscf.org>
> > Message-ID: <6933968b-d5f1-fb6b-c518-e47ca4ce6da8 at cnr.it>
> > Content-Type: text/plain; charset=windows-1252; format=flowed
> >
> > Dear Alan,
> >      I think that there is no problem in doing a G=0 response
> > with a shifted mesh. The response is at G=0, hence it couples
> > wfcs at the same k. The susceptibility depends a lot on k-points
> > sampling and if your system has a vanishing band gap, convergence
> > can be a nightmare.
> > By default the macroscopic shape is diagonal:
> >    nmr_macroscopic_shape(:,:) = 0.d0
> >    nmr_macroscopic_shape(1,1) = 2.d0 / 3.d0
> >    nmr_macroscopic_shape(2,2) = 2.d0 / 3.d0
> >    nmr_macroscopic_shape(3,3) = 2.d0 / 3.d0
> > You can change the component (demagnetizing field) in the input file.
> >
> > Good luck for your calculations!
> >
> > Best,
> >      Davide
> >
> >
> >
> > On 05/12/2017 07:47 PM, Ambrozio wrote:
> >> Dear QE users and Developers,
> >>
> >> I'm working with NMR calculations in Gipaw. Recently I did some
> shielding
> >> calculations and I have some questions regarding the magnetic
> susceptibility.
> >> The article from developers Mauri et al (*PRL 77, 26, 1996*) explain
> that the
> >> shielding of a bulk of a periodic system is also periodic (i.e. has the
> same
> >> periodicity of *G*, the reciprocal lattice vectors), and it is
> proportional to
> >> the magnetic susceptibility matrix. In the paper Mauri did a short
> discussion
> >> about the macroscopic susceptibility, which is calculated at *G=0*.
> Follow my
> >> questions:
> >>
> >> i) Assuming that the macroscopic susceptibility is calculating at gamma
> point
> >> (*G=0*) and depends of the sample's shape, Does make sense to do a NMR
> >> calculation with automatic kpoints (monkhorst pack grid)  that does not
> include
> >> the gamma point? It is mandatory to including the gamma point when the
> shape
> >> correction is .true.?
> >>
> >> ii) Does the susceptibility depends of the supercell size? I found very
> >> different susceptibilities for the same material (AB graphite) changing
> the
> >> supercell size.
> >>
> >> iii) Why the susceptibility  matrix is not diagonal when the shape
> correction is
> >> .true.? Assuming the Mauri paper I think it doens't make sense. Help me
> to
> >> understand...
> >>
> >>
> >> I appreciate any help,
> >>
> >> Thanks in advance,
> >>
> >>
> >> Alan.
> >>
> >>
> >>
> >> --
> >>
> >> Alan J. Romanel Ambrozio
> >> Bacharel em F?sica
> >> Mestre em Eng. de Materiais
> >> Doutorando em F?sica - PPGFis
> >>
> >>
> >>
> >
> > --
> > +--------------------------------------------------------------+
> >    Davide Ceresoli
> >    CNR Institute of Molecular Science and Technology (CNR-ISTM)
> >    c/o University of Milan, via Golgi 19, 20133 Milan, Italy
> >    Email: davide.ceresoli at cnr.it
> >    Phone: +39-02-50314276, +39-347-1001570 (mobile)
> >    Skype: dceresoli
> >    Website: http://sites.google.com/site/dceresoli/
> > +--------------------------------------------------------------+
> >
> >
> > ------------------------------
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
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> >
> > End of Pw_forum Digest, Vol 118, Issue 12
> > *****************************************
> >
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>
>
> --
> Pietro Bonfa'
> Dipartimento di Fisica e Scienze della Terra "Macedonio Melloni"
> Viale delle Scienze 7A
> 43124 Parma - Italy
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
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>
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