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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

1) Have you checked the convergence on relaxed cells or unrelaxed one
? Relaxed surfaces usually takes more layers than unrelax slabs.
2)  In my thesis I have computed the forces in unrelaxed slabs of
tantalum with different surface orientation. It happens that for some
surfaces the forces have a much larger depth than for others. For
instance, in tantalum (a BCC metal) forces decreases much more slowly
for [110] surface than for [111] (see  right figure in
http://anglade.googlepages.com/these-anglade.pdf p61). This do not
tell for sure that the relaxation will be stronger and that the number
of layers must be higher. Yet it must be checked...

On 2/3/07, ha sa <ha_sadi@yahoo.com> wrote:
> Hi,
> I actually checked the convergence with respect to 100
> surface and used the same values for 111 and 110
> surfaces, but may be it is not sufficient for 110, I
> shall try increasing no. of atomic layers. Thank you
> very much for your help.
>
> --- Anglade Pierre-Matthieu <anglade@gmail.com> wrote:
>
> > Hi,
> > it looks like your input  are fine. However are you
> > sure they are
> > converged with respect with respect to numbers of
> > atomic layers
> > (especially for the relaxed case) and energy cutoff
> > ?
> > regards
> >
> > PMA
> >
> > On 1/22/07, ha sa <ha_sadi@yahoo.com> wrote:
> > > Dear abinit users,
> > >   I calculated the surface energy for the three
> > low
> > > index surfaces for fcc transition metal ,the usual
> > > results is to get the highest surface energy for
> > 110
> > > surface(most open structure) and the lowest for
> > 111
> > > surface (most close packed) my results are quite
> > > normal except the following
> > >           unrelaxed S.E.       relaxed S.E.
> > > 110         3.19                  2.95
> > > 100         3.06                  2.98
> > > the unrelaxed surface energy is according to the
> > > normal picture of fcc metal,but the relaxed
> > surface
> > > energy of 110 surface is slightly smaller than
> > that of
> > > 100 surface.
> > > the above results were obtained using GGA, the
> > > experimental surface energy for an average Ir
> > surface
> > > is 3.00 J/m^2. similar behavior is obtained usind
> > LDA.
> > >
> > > I attached my input file for both surfaces.
> > > What could be the source of this behavior?
> > > thanks in advance.
> > >
> > > Hanan
> > >
> > >Hanan
> > >
> > >
> >
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> >
> >
> > --
> > Pierre-Matthieu Anglade
> >
>
>
>
>
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--
Pierre-Matthieu Anglade