The ABINIT Users Mailing List ( CLOSED )

[Michel Côté <michel.cote@umontreal.ca>]

Title: Re: [abinit-forum] Li15Si4, convergence of ecut/kpt

Hello Vincent,

I had a close look at your output file, and it seems that you are facing a typical case of a ghost state. If you look at the eigenvalues output, you will see for certain k-points abnormally low values which are a sign of a ghost state. Moreover, your scf convergences are very fast, 7 or 8 iterations, this is also a sign of a ghost state. I suggest that you check your pseudopotentials.

Best wishes,

Michel


Le 28/05/07 06:28, « Anglade Pierre-Matthieu » <anglade@gmail.com> a écrit :

> Hi,
>
> Usualy convergence in ecut is considered independant from convergence in kpt. You can trust your 2 2 2 grid about that I think. It looks like there is a problem with the parallel version of abinit you use. Does it stand the parallel tests correctly ? 
> By the way have you tryed to see what's happening if you treat your supercell has metallic (occopt 3/4.. and tsmear)?
> What do you mean when you say that Abinit crashes with occopt parameters different from zero ? 
> regards
>
> Pierre-Matthieu Anglade
>
> On 5/28/07, vincent.chevrier@dahn.phys.dal.ca < vincent.chevrier@dahn.phys.dal.ca <mailto:vincent.chevrier@dahn.phys.dal.ca> > wrote:
> > Hi,
> > I've recently begun using Abinit and have gone through the basic tutorials. I'm trying to run an energy calculation of Li15Si4. The primitive cell is sizeable (30 Li, 8 Si) and I'm having difficulty establishing the appropriate ecut and ngkpt (or nkpt). 
> >
> > Here's a table of energies (in Ha). If anyone could tell me why the energy starts varying so wildly as the k points are increased or if anyone has any recommendations as to which parameters I should use I would really appreciate it! 
> >
> > ecut\ngkpt (nkpt)
> >
> >         2 2 2 (2)       4 4 4 (6)      10 10 10 (44)   12 12 12 (68)
> > 30      -42.500550      -42.500085      -56.940709      -43.130515
> > 35      -42.500777      -42.500314      -61.734328       -42.554030
> > 40      -42.500897      -42.500449      -86.955397      -149.902062
> > 45      -42.500918      -42.500504      -42.604657      -260.973168
> > 50      -42.500920      -42.500457      -42.566132      -158.776883 
> > 55      -42.500928      -42.500670      -44.279878      -48.285954
> > 60      -42.500936      -42.500489      -75.221022      -43.411153
> >
> > The .in, .out and log files, of the ngkpt 12 12 12 case are at the following address (if you're really interested!). The other energies were generated with the exact same input files with only the ngkpt changed. 
> > http://myweb.dal.ca/chevrier/abinit/ecut_LDA_22.in
> > http://myweb.dal.ca/chevrier/abinit/ecut_LDA_22.out  <http://myweb.dal.ca/chevrier/abinit/ecut_LDA_22.out> 
> > http://myweb.dal.ca/chevrier/abinit/log_Li15Si4_ecut_LDA_22
> >
> > I'm running this with the parallel version.
> > Thanks!
> >
> > Vincent Chevrier 
> > PhD Candidate
> > Physics Department
> > Dalhousie University


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  Michel Cote                          tel: +1 (514) 343-5628     
  Professeur agrégé                   fax: +1 (514) 343-2071               
  Département de physique 
  Université de Montréal 
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  Canada                   www.phys.umontreal.ca/~michel_cote 
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