Dear Hui Wang and Gabriele Sclauzero<br><br>Thank you for your replies. I just start to learn how to use pwscf and there are many knowledge and skills that I should learn. Anyway, I will read more references and make more tests.<br>
<br><div class="gmail_quote">On Wed, Nov 11, 2009 at 7:04 PM, <span dir="ltr"><<a href="mailto:pw_forum-request@pwscf.org">pw_forum-request@pwscf.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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Today's Topics:<br>
<br>
1. Re: How to set ecutwfc and ecutrho (xirainbow)<br>
2. Re: How to set ecutwfc and ecutrho (Gabriele Sclauzero)<br>
3. graphene scf calculation (Vit)<br>
4. Re: Descriptions of FHI and UPF formats? (Lorenzo Paulatto)<br>
5. Re: Descriptions of FHI and UPF formats? (Paolo Giannozzi)<br>
6. Re: graphene scf calculation (Eyvaz Isaev)<br>
7. Re: graphene scf calculation (xirainbow)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Wed, 11 Nov 2009 08:38:26 +0000<br>
From: xirainbow <<a href="mailto:nkxirainbow@gmail.com">nkxirainbow@gmail.com</a>><br>
Subject: Re: [Pw_forum] How to set ecutwfc and ecutrho<br>
To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID:<br>
<<a href="mailto:21fbc4790911110038g1d398803o932dde721606d3e7@mail.gmail.com">21fbc4790911110038g1d398803o932dde721606d3e7@mail.gmail.com</a>><br>
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<br>
Dear Li?<br>
<br>
<br>
I am curious about the calculation speed related to "ecutwfc" and "ecutrho".<br>
> As indicated in the tutorial, ecutwfc represents the energy cutoff (Ry) and<br>
> ecutrho refers to kinetic energy cutoff for charge density and potential. I<br>
> cannot fully understand the meaning of that brief description.<br>
<br>
If you use Norm-concerving PP, you can just omit the parameter "ecutrho".<br>
If you use Ultra-soft PP, you must set "ecutrho" as (8~12)X"ecutwfc".<br>
You will fully understand the "ecutrho" after reading some paper about<br>
Ultra-soft PP?? (For example?PRB, 41 7892)<br>
<br>
<br>
<br>
> From my experience (vasp), the larger the energy cutoff, the slower the<br>
> calculation would be, but more accurate.<br>
<br>
Yes? it is true for PWscf, too.<br>
<br>
I just would like to know how to set the experience values of the two flags<br>
> for the case of metal bulk (and surface) and metal oxide bulk (and surface)?<br>
> Thank you.<br>
><br>
I think, the value is different with different kind of metal.<br>
You can take a convergence test to get proper "ecutrho" and "ecutwfc" ??<br>
<br>
____________________________________<br>
Hui Wang<br>
School of physics, Nankai University, Tianjin, China<br>
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Message: 2<br>
Date: Wed, 11 Nov 2009 09:58:49 +0100<br>
From: Gabriele Sclauzero <<a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a>><br>
Subject: Re: [Pw_forum] How to set ecutwfc and ecutrho<br>
To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID: <<a href="mailto:4AFA7CC9.6090108@sissa.it">4AFA7CC9.6090108@sissa.it</a>><br>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed<br>
<br>
Dear Jiaye,<br>
<br>
Jiaye Li wrote:<br>
> Dear users<br>
><br>
> I am curious about the calculation speed related to "ecutwfc" and<br>
> "ecutrho". As indicated in the tutorial, ecutwfc represents the energy<br>
> cutoff (Ry) and ecutrho refers to kinetic energy cutoff for charge<br>
> density and potential. I cannot fully understand the meaning of that<br>
<br>
More precisely, ecutwfc and ecutrho are the kinetic energy cutoff of the plane wave basis<br>
used to describe the wavefunctions and the charge density, respectively.<br>
<br>
> brief description. From my experience (vasp), the larger the energy<br>
> cutoff, the slower the calculation would be, but more accurate. I just<br>
<br>
That's right and I think should be a general consideration valid for any code using plane<br>
waves. I would say "longer", rather than "slower" (which I feel more appropriate with<br>
regard to the optimization of a code or the performance of a computer).<br>
<br>
<br>
> would like to know how to set the experience values of the two flags for<br>
> the case of metal bulk (and surface) and metal oxide bulk (and surface)?<br>
<br>
The choice of the cutoffs depends only on the pseudopotentials you are using and on which<br>
quantities you are interested in (for instance, magnetic properties are harder to converge<br>
wrt total energy). Once you've chosen your PPs you can test convergence of the energy wrt<br>
to cutoffs in the cheapest system (usually in the bulk). The threshold of convergence is<br>
somehow your choice: personally I don't go below 1mRy since this is the expected order of<br>
magnitude of the errors due to PPs.<br>
For normconserving PPs you don't need to specify ecutrho, since the default (4*ecutwfc) is<br>
good (you can try to figure out why, writing down the charge density in terms of the PW<br>
expansion of the wavefunctions).<br>
For ultrasoft PPs you will need higher ecutrho due to the augmentation terms in the charge.<br>
<br>
Try to read some literature about pseudopotential and ask to some experienced people<br>
working next door and, of course, experience yourself by trying.<br>
<br>
HTH<br>
<br>
GS<br>
<br>
<br>
> Thank you.<br>
><br>
> --<br>
> Sincerely yours<br>
><br>
> Jiaye Li<br>
><br>
><br>
> ------------------------------------------------------------------------<br>
><br>
> _______________________________________________<br>
> Pw_forum mailing list<br>
> <a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
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<br>
--<br>
<br>
<br>
o ------------------------------------------------ o<br>
| Gabriele Sclauzero, PhD Student |<br>
| c/o: SISSA & CNR-INFM Democritos, |<br>
| via Beirut 2-4, 34014 Trieste (Italy) |<br>
| email: <a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a> |<br>
| phone: +39 040 3787 511 |<br>
| skype: gurlonotturno |<br>
o ------------------------------------------------ o<br>
<br>
<br>
------------------------------<br>
<br>
Message: 3<br>
Date: Wed, 11 Nov 2009 15:42:13 +0600<br>
From: Vit <<a href="mailto:vitruss@gmail.com">vitruss@gmail.com</a>><br>
Subject: [Pw_forum] graphene scf calculation<br>
To: "PWSCF Forum" <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID: <<a href="mailto:op.u2748ll9ijpzuf@arch.che.intra.net">op.u2748ll9ijpzuf@arch.che.intra.net</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Dear all!<br>
I'm trying to plot graphene band structure as a part of computations of<br>
carbon based composites. But scf calculation for graphene can't achieve<br>
convergence. I've tried different mixing_beta, mixing_mode, degaus ant<br>
ecutwfc. The example input file is attached. Could you please tell me<br>
which parameters I should tune to achieve convergence?<br>
<br>
Thanks in advance,<br>
Koroteev Victor<br>
PhD student,<br>
Nikolaev Institute of Inorganic Chemistry SB RAS<br>
Novosibirsk, Russian Federation.<br>
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Message: 4<br>
Date: Wed, 11 Nov 2009 10:46:03 +0100<br>
From: "Lorenzo Paulatto" <<a href="mailto:paulatto@sissa.it">paulatto@sissa.it</a>><br>
Subject: Re: [Pw_forum] Descriptions of FHI and UPF formats?<br>
To: "PWSCF Forum" <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID: <op.u275e10ta8x26q@paulax><br>
Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes<br>
<br>
In data 11 novembre 2009 alle ore 02:17:23, Brad Malone<br>
<<a href="mailto:brad.malone@gmail.com">brad.malone@gmail.com</a>> ha scritto:<br>
> Is<br>
> <a href="http://quantum-espresso.org/wiki/index.php/Unified_pseudopotential_format" target="_blank">http://quantum-espresso.org/wiki/index.php/Unified_pseudopotential_format</a><br>
> up to date?<br>
<br>
Yes, it is. There is a new UPF format which is quite different (the<br>
description is currently sitting in my hard disk), but fhi2upf converts to<br>
the one described on the web page.<br>
<br>
> If so, any explanation for FHI then? It would be nice to not<br>
> simply get an understanding of the format by looking at fhi2upf.f90,<br>
> since I then might not be able to tell what assumptions result in it<br>
> occasionally<br>
> not working.<br>
<br>
I see you point, but I don't know of any such description. You may be<br>
luckier on the abinit web site, although a quick google search didn't find<br>
anything for me.<br>
<br>
regards<br>
<br>
--<br>
Lorenzo Paulatto<br>
SISSA & DEMOCRITOS (Trieste)<br>
phone: +39 040 3787 511<br>
skype: paulatz<br>
www: <a href="http://people.sissa.it/%7Epaulatto/" target="_blank">http://people.sissa.it/~paulatto/</a><br>
<br>
*** save italian brains ***<br>
<a href="http://saveitalianbrains.wordpress.com/" target="_blank">http://saveitalianbrains.wordpress.com/</a><br>
<br>
<br>
------------------------------<br>
<br>
Message: 5<br>
Date: Wed, 11 Nov 2009 10:50:14 +0100<br>
From: Paolo Giannozzi <<a href="mailto:giannozz@democritos.it">giannozz@democritos.it</a>><br>
Subject: Re: [Pw_forum] Descriptions of FHI and UPF formats?<br>
To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID: <<a href="mailto:4AFA88D6.9060205@democritos.it">4AFA88D6.9060205@democritos.it</a>><br>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed<br>
<br>
Brad Malone wrote:<br>
<br>
> If so, any explanation for FHI then?<br>
<br>
FHI = Fritz Haber Institute...some time ago I looked for<br>
documentation of their format and found nothing<br>
<br>
P.<br>
--<br>
Paolo Giannozzi, Democritos and University of Udine, Italy<br>
<br>
<br>
------------------------------<br>
<br>
Message: 6<br>
Date: Wed, 11 Nov 2009 03:04:08 -0800 (PST)<br>
From: Eyvaz Isaev <<a href="mailto:eyvaz_isaev@yahoo.com">eyvaz_isaev@yahoo.com</a>><br>
Subject: Re: [Pw_forum] graphene scf calculation<br>
To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID: <<a href="mailto:304105.15826.qm@web65702.mail.ac4.yahoo.com">304105.15826.qm@web65702.mail.ac4.yahoo.com</a>><br>
Content-Type: text/plain; charset=us-ascii<br>
<br>
Dear Victor,<br>
<br>
<br>
> But scf calculation for graphene can't<br>
> achieve convergence. I've tried different mixing_beta,<br>
> mixing_mode, degaus ant ecutwfc. The example input file is<br>
> attached. Could you please tell me which parameters I should<br>
> tune to achieve convergence?<br>
<br>
There are several issues (according to your input file) that can affect on convergence in your case. But the main reason, most likely, is k-mesh grid, using 16x16x1 grid the convergence was OK.<br>
<br>
Please pay attention, 16x16x1, because you simulate 2D case.<br>
<br>
For Ultrasoft PsP you should use ecutrho about (8-12) times larger than ecutwfc.<br>
<br>
You have 2 carbon atoms with 4 valence electrons, so, you do not need 8 bands (only 4 is enough), if graphene is semiconducting. In this case you can omit degauss (not sure it is used, if you did not specify "occupations" keyword). Otherwise use keywords specific for metallic case<br>
(occupations='smearing', smearing='XYZ', degauss=LKJ).<br>
<br>
I used mixing_beta=0.1 and mixing_mode-'local-TF', too.<br>
<br>
Bests,<br>
Eyvaz.<br>
<br>
<br>
-------------------------------------------------------------------<br>
Prof. Eyvaz Isaev,<br>
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia,<br>
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden<br>
Condensed Matter Theory Group, Uppsala University, Sweden<br>
<a href="mailto:Eyvaz.Isaev@fysik.uu.se">Eyvaz.Isaev@fysik.uu.se</a>, <a href="mailto:isaev@ifm.liu.se">isaev@ifm.liu.se</a>, <a href="mailto:eyvaz_isaev@yahoo.com">eyvaz_isaev@yahoo.com</a><br>
<br>
<br>
--- On Wed, 11/11/09, Vit <<a href="mailto:vitruss@gmail.com">vitruss@gmail.com</a>> wrote:<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
------------------------------<br>
<br>
Message: 7<br>
Date: Wed, 11 Nov 2009 11:04:17 +0000<br>
From: xirainbow <<a href="mailto:nkxirainbow@gmail.com">nkxirainbow@gmail.com</a>><br>
Subject: Re: [Pw_forum] graphene scf calculation<br>
To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID:<br>
<<a href="mailto:21fbc4790911110304g39d379fam4e3f69b79065d9ed@mail.gmail.com">21fbc4790911110304g39d379fam4e3f69b79065d9ed@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Dear Victor:<br>
I look at your input file and notice :"K_POINTS {automatic} 24 24 24 0 0 0"<br>
I think there is no need to set kz=24, because you deal with a two dimension<br>
graphene.<br>
Of couse, setting kz=24 is not wrong.<br>
<br>
The following is my <a href="http://graphene.rx.in" target="_blank">graphene.rx.in</a> (not <a href="http://scf.in" target="_blank">scf.in</a>) for graphene.<br>
I calculated it about half a year ago, and it went well??<br>
I also put my graphene's results at<br>
<a href="http://blog.sina.com.cn/s/blog_5f15ead20100c9fu.html" target="_blank">http://blog.sina.com.cn/s/blog_5f15ead20100c9fu.html</a><br>
I hope it can help you??<br>
<br>
&CONTROL<br>
calculation = 'vc-relax' ,<br>
restart_mode = 'from_scratch' ,<br>
outdir = '/home/raman/graphene/g-monolayer/' ,<br>
pseudo_dir = '/home/raman/espresso-4.0.4/pseudo/' ,<br>
etot_conv_thr = 1.0e-7 ,<br>
forc_conv_thr = 1.0e-7 ,<br>
tstress = .true. ,<br>
tprnfor = .true. ,<br>
/<br>
&SYSTEM<br>
ibrav = 4,<br>
celldm(1) = 4.608737,<br>
celldm(3) = 4.536666,<br>
nat = 2,<br>
ntyp = 1,<br>
ecutwfc = 60.D0 ,<br>
nosym = .false. ,<br>
nbnd = 8,<br>
nelec = 8,<br>
tot_charge = 0.000000,<br>
occupations = 'fixed' ,<br>
/<br>
&ELECTRONS<br>
conv_thr = 1.D-8 ,<br>
mixing_mode = 'local-TF' ,<br>
mixing_beta = 0.7D0 ,<br>
/<br>
&IONS<br>
ion_dynamics = 'bfgs' ,<br>
pot_extrapolation = 'second_order' ,<br>
wfc_extrapolation = 'second_order' ,<br>
/<br>
&CELL<br>
cell_dynamics = 'bfgs' ,<br>
press_conv_thr = 0.2 ,<br>
cell_dofree = 'xyz' ,<br>
/<br>
ATOMIC_SPECIES<br>
C 12.00000 C.pz-rrkjus.UPF<br>
ATOMIC_POSITIONS crystal<br>
C 0.000000000 0.000000000 0.000000000 1 1 1<br>
C 0.333333333 -0.333333333 0.000000000 1 1 1<br>
K_POINTS automatic<br>
23 23 1 0 0 0<br>
<br>
<br>
____________________________________<br>
Hui Wang<br>
School of physics, Nankai University, Tianjin, China<br>
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End of Pw_forum Digest, Vol 29, Issue 31<br>
****************************************<br>
</blockquote></div><br><br clear="all"><br>-- <br>Sincerely yours<br><br>Jiaye Li<br><br>