[Wien] K-point extraction

[Peter Blaha]

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
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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