[Pw_forum] A problem about Ex.12

[mohsen modaresi]

Dear Stefano
Thanks for your answer
Why they used this kind of lattice? there are many another example like
this.

Mohsen Modaresi

On Thu, Nov 26, 2009 at 6:26 PM, Stefano de Gironcoli <degironc at sissa.it>wrote:

> Dear mohsen modaresi
>
>  you can describe an fcc crystal in an FCC bravais lattice with one atom
> per cell or in a Simple Cubic cell with 4 atoms per cell or in a
> tetragonal cell with 2 atoms per cell or in many other  equivalent ways.
> Why it is done using tetragonal lattice in that particular  example I
> don't know but it may  be due  to  the need of  using some particular
> orientation or orthonormal  Bravais vectors or some other reason.
> Hope this helps,
>
> stefano.
>
> mohsen modaresi wrote:
> > Hi dear users
> > I read Ex.12 and run it, In the input file for Al (al.scf.in
> > <http://al.scf.in> ) i see this part
> >      ibrav = 6,
> >     celldm(1) =5.3,
> >     celldm(3) =1.414,
> > But we konw that Al has F.CC structure, Why they set ibarav=6 not 2, I
> > faced with this problem in example 11 in the Want package.
> > Thanks for answers
> >
> > Mohsen Modaresi
> > Msc. Student of Solid State Physics,
> > Department of Physics,Ferdowsi University of Mashhad,
> > Iran.
> >
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