[Pw_forum] ecutwfc

[raha khalili]

Very thanks Axel.


On Wed, Feb 26, 2014 at 4:39 PM, Axel Kohlmeyer <akohlmey at gmail.com> wrote:

> On Wed, Feb 26, 2014 at 7:09 AM, raha khalili <khadije.khalili at gmail.com>
> wrote:
> >
> > Firstly, i have to say thank you very much for your helps.
> > So sorry for too many questions. I changed the pseudopotentials to
> > nonrelativistic, except Au: H.pz-rrkjus.UPF, ... . Therefore, my first
> > ecutwfc and ectrho will be 27 and 378, respectively. I am in right way?
>
> you seem to be new to the subject of electronic structure calculations
> with a plane wave pseudopotential DFT code, thus a word of warning is
> in place:
> do not start with your (complex) research project right away. you
> *have* to practice with (simple) materials, where the results of
> calculations are known and you can gain experience how to obtain the
> kind of results you are looking for. if you do this with a "new" or
> "complex" system  (or one that is both), you will never know, if
> something is the correct answer or the result of a typo or a
> misconception or just plain wrong. working with simple problems with
> know results takes away this insecurity and you can verify, if you are
> doing your calculations correctly.
>
> you should not guess and then ask a mailing list for confirmation, you
> have to know by yourself based on tests. those tests, again, are much
> easier to do with simple systems.
>
> axel.
>
> > Raha
> >
> >
> > On Wed, Feb 26, 2014 at 2:50 PM, Bertrand SITAMTZE <siyouber at yahoo.fr>
> > wrote:
> >>
> >> Dear Khadije,
> >>
> >> Usually, for US pseudopotentials, the charge density cutoff is 6 to 12
> >> times the wavefunctions cutoff.
> >> The final value to be considered being dictated by the hardest
> >> pseudopotential in your list. For your Au pseudopotential, you should
> use
> >> something like ecutrho=14*ecutwfc which will be CPU consuming because
> the
> >> other pseudopotentials require less.
> >> Therefore, either you use such value for ecutrho, or you search for
> >> another pseudopotentials for C and Au. Whatever the case, a convergence
> test
> >> is welcomed!
> >>
> >> Bertrand
> >>
> >> ******CURRENT ADDRESS
> >> IMMM, UMR CNRS 6283
> >>  Université du Maine
> >> Le Mans, France
> >> Tél: +33 6 67 61 52 15
> >> e-mail: siyouber at yahoo.fr
> >>               Bertrand.Sitamtze at univ-lemans.fr
> >> ****************************************
> >>
> >>
> >> Le Mercredi 26 février 2014 12h00, raha khalili
> >> <khadije.khalili at gmail.com> a écrit :
> >> Daer PW users
> >>
> >> I'm doing calculations on a system consist of 5 atoms. In their
> ultrasoft
> >> pseudopotential files are suggested different minimum ecutwfc and
> ecutrho.
> >> S: Suggested minimum cutoff for wavefunctions:  18. Ry
> >>     Suggested minimum cutoff for charge density:  77. Ry
> >>
> >> N: Suggested minimum cutoff for wavefunctions:  39. Ry
> >>     Suggested minimum cutoff for charge density: 263. Ry
> >>
> >> H: Suggested minimum cutoff for wavefunctions:  46. Ry
> >>     Suggested minimum cutoff for charge density: 221. Ry
> >>
> >> C: Suggested minimum cutoff for wavefunctions:  37. Ry
> >>     Suggested minimum cutoff for charge density: 317. Ry
> >>
> >> Au: Suggested minimum cutoff for wavefunctions:  27. Ry
> >>     Suggested minimum cutoff for charge density: 391. Ry
> >>
> >> What is the best ecutwfc and ecutrho for such system?
> >> Best Regards
> >> --
> >> Khadije Khalili
> >> Ph.D Student of Solid-State Physics
> >> Department of Physics
> >> University of Mazandaran
> >> Babolsar, Iran
> >> kh.khalili at stu.umz.ac.ir
> >>
> >>
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> >>
> >>
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> >
> >
> >
> >
> > --
> > Khadije Khalili
> > Ph.D Student of Solid-State Physics
> > Department of Physics
> > University of Mazandaran
> > Babolsar, Iran
> > kh.khalili at stu.umz.ac.ir
> >
> >
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>
>
>
> --
> Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
> College of Science & Technology, Temple University, Philadelphia PA, USA
> International Centre for Theoretical Physics, Trieste. Italy.
>
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-- 
Khadije Khalili
Ph.D Student of Solid-State Physics
Department of Physics
University of Mazandaran
Babolsar, Iran
kh.khalili at stu.umz.ac.ir
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