[Pw_forum] Bonding Energy

[Eyvaz Isaev]

Dear Felipe,

There is no disagree, sure more k-points for small
systems as I quoted in my previous mail, but \gamma
point for a big cell (supercell) with large cell
parameters even there is just one atom. 

Regards,
Eyvaz.
 
--- FELIPE VALENCIA <felipe at titan.ipicyt.edu.mx>
wrote:
> > 1. You should not use only \Gamma point for small
> > systems (where number of atoms <10). Rather you
> have
> > to use integration via Monkhorst-Pack k-points
> which
> > are generated automatically if you enter:
> > 
> > K_POINTS{automatic}
> > 10 10 10 
> > 0 0 0 
> > 
> > which means that k-points will be generated
> according
> > to Monkhorst-Pack schem,  each direction of
> reciprocal
> > basis vectors is divided by 10 and there is no
> shift
> > of  origin of k-vectors.
> > 
> 
> Concernig this point I disagree with Eyvaz, It is
> true that in your
> actual input files you are dealing with  small
> systes, but if your final
> goal is to study  molecular systems, you are going
> to increase the lattice
> parameter... the real system has no peridicity (i.e.
> an infinite lattice
> parameter) and the reciprocal space reduces then to
> the gamma point, so
> that Gamma point seems to me the logical  for
> molecules...
> 
> Felipe
> 
> 
> 
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