[Wien] K-point extraction

[Laurence Marks]

It is sometimes useful to use a non-standard bulk reference which has
the same symmetry as your surface. For instance you can transform to a
hexagonal Cu cell with axes 1/2[1-10], 1/2[-101] and [111], and change
some of the Cu's to Cu1, Cu2 etc in the case.struct file. It's then
easier to get consistency between the k-points and also with RKMAX.

On 10/10/06, Peter Blaha <pblaha at theochem.tuwien.ac.at> wrote:
> a) Very interesting that you converge EFG and MMI for bulk Cu.
> Fcc Cu does not have and EFG nor any magnetic moment.
>
> b) From your lattice parameters one can see that you want to study
> Cu(111) surface. If the lattice parameters differ from the original cell
> by factors of sqrt(2) or sqrt(3) then you CANNOT make an equivalent
> k-mesh. All you can do is coming as close as possible and use a mesh
> close to eg. 12 / sqrt(2)
>
> Furthermore please note: By selecting eg. 7-layers you have "implicitly"
> also set a k-mesh in the c-direction (backfolding). This k-mesh,
> however, cannot be "improved" (unless you use more layers).
>
>
> John Appleton schrieb:
> > Dear WIEN2k user,
> >
> > suppose I use a 12x12x12 k-point mesh to converge
> > EFG and MMI for bulk fcc Cu. Now I want to find a smart
> > way to extrapolate the k-points for a (2x2) supercell
> > containing a 7-layer slab and 12 A vacuum. Along
> > z is easy as only 1 k point is required. For
> > the 2D region of the supercell, a=b=L*sqrt(2) gamma=120,
> > L being the bulk lattice constant but for the bulk cell
> > a=b=L and gamma=90. I don't know how to extend
> > the bulk 2D mesh to the supercell 2D mesh.  I
> > need a technical sound advice.
> > Any help would be much appreciated.
> >
> > Thank you
> >
> >
> >
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> --
>
>                                        P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW:
> http://info.tuwien.ac.at/theochem/
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-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
http://www.numis.northwestern.edu