Dear Mohammadreza Hosseini,
Please try to understand the concept of "back-folding" when using
super-cells hen calculating band structures. There are programs to
"unfold" the band structure, for example by Jonas Björk.
And please do not reply directly to the Digest-messages; use an
appropriate Subject and post only the relevant part of the Digest-message
- or start a new thread, if there is nothing in the digested message that
you refer to, like in your case. Thank you. :)
Greetings from the aeroport of Lisbon,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / ari.p.seitso...@iki.fi / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Sun, 14 May 2017, Mohammadreza Hosseini wrote:
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
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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.paula...@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@pwscf.org>
Message-ID: <1728518.gkaUiGcZ5e@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
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Message: 2
Date: Sat, 13 May 2017 16:09:02 +0200
From: Davide Ceresoli <davide.ceres...@cnr.it>
Subject: Re: [Pw_forum] Gipaw - Magnetic susceptibility
To: PWSCF Forum <pw_forum@pwscf.org>
Message-ID: <6933968b-d5f1-fb6b-c518-e47ca4ce6...@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.ceres...@cnr.it
Phone: +39-02-50314276, +39-347-1001570 (mobile)
Skype: dceresoli
Website: http://sites.google.com/site/dceresoli/
+--------------------------------------------------------------+
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