The ABINIT Users Mailing List ( CLOSED )

[Pawel Scharoch <Pawel.Scharoch@pwr.wroc.pl>]

   Dear Pierre-Matthieu,

     I would be very interested in any didactical material concerning
 DFT-PW,  and I would be obliged if you could send me some,

  with best regards,

  Pawel

----- Oryginalna wiadomość -----
Od: Anglade Pierre-Matthieu <anglade@gmail.com>
Data: Piątek, Sierpień 3, 2007 8:57 am
Temat: Re: [abinit-forum] problem for ecut
Do: forum@abinit.org

> Hi
> 
> There is no such "true" ecut:
> the cutoff energy describes how many plane waves wil be used to
> describe the wave functions within your calculations. The more plane
> waves the more frequencies will be depicted and then the more accurate
> will be your calculation.
> You have to find an equilibrium between the computation time and the
> accuracy of your calculation. That's why we usually search the minimum
> ecut that accurately describe the system. Here "accurately" may
> strongly depends on the properties you want to examine. If you 
> have no
> special requirement an absolute convergence of about 1e-3 Ha is
> usually considered correct because pseudopotentials tends to reproduce
> the full electron calculation on which they are based to this
> precision. That is, you will (almost) never get more physics by having
> something better converged. However some problems may require
> convergency of ecut down to 1e-4 or 1e-5 Ha.
> 
> You can find examples of how to find the correct value of ecut in the
> Abinit tutorials. HAve you tryed them and reproduce the steps depicted
> there in your calculations ? If you want some comments on your own
> results, please send some details about your input and output.
> 
> Also,  I'm just back from a summer school where I have presented
> Abinit to very beginners in DFT - PW calculations. Then, I have lots
> of didactical materials where I insist on this very problem. If you
> like I can send those PDF to you.
> 
> regards
> 
> pierre-matthieu Anglade
> 
> On 8/2/07, m_mousavi1980@yahoo.com <m_mousavi1980@yahoo.com> wrote:
> >
> > Hi
> >
> > I have a question
> > How can i understand which ecut for zno is true.
> > I get ecut 62.01
> > thanks
> > best regard
> >
> 
> 
> -- 
> Pierre-Matthieu Anglade
> 
>
begin:vcard
n:Scharoch;Pawel
fn:Pawel Scharoch 
tel;work:713202330
url:www.if.pwr.wroc.pl/~scharoch
org:Wroclaw University of Technology;Institute of Physics
adr:;;Wyb. Wyspianskiego 27;Wroclaw;;50-370;Poland
version:2.1
email;internet:Pawel.Scharoch@pwr.wroc.pl
title:dr
end:vcard