[gpaw-users] Inplane force != zero

[Jens Jørgen Mortensen]

On Tue, 2010-06-01 at 19:33 -0400, Duy Le wrote:
> Some components go up to 0.05A/eV. I know the egg box effect, but I
> don't think they can be that huge.

I think they can be.  Hopefully the displacements you get from these
egg-box forces are small enough to ignore.

JJ

>  I used h=0.20A. If  h is reduced to 0.18A, those non zero forces
> could go up to 0.04A/eV.   
> 
> 
> I don't really understand your 2nd question. However, the structure
> was generated by using ase.structure.bulk and grid-mesh was generated
> by gpts(72,72,164). I don't see any problem in regarding the symmetry
> of structure and grid mesh.
> 
> --------------------------------------------------
> Duy Le
> PhD Student
> Department of Physics
> University of Central Florida.
> 
> "Men don't need hand to do things"
> 
> 
> On Tue, Jun 1, 2010 at 6:07 PM, Ask Hjorth Larsen <askhl at fysik.dtu.dk>
> wrote:
>         Dear Duy Le
>         
>         
>         On Tue, 1 Jun 2010, Duy Le wrote:
>         
>                 Dear All,I was relaxing 5 layer of Cu(111). For
>                 (1x1x5) slab, everything is
>                 great. However, for (5x5x5) slab, It is weird that the
>                 in-plane components
>                 of forces (in Oxy plane) are not zero (they should be
>                 zero because
>                 of symmetry). 
>                 I don't know what causes the problem (or maybe not).
>                 Any comment will be great!
>         
>         
>         How nonzero are they?  Is the system symmetric also with
>         respect to the structure of grid points?
>         
>         Regards
>         Ask
> 
> 
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