[Wien] Number of k points

[Peter Blaha]

No.
This depends on the details of your reaction.

The correct procedure is to use "converged" k-meshes, i.e. test each
single calc. for k-convergence such that E-tot is changing less than your required
accuracy.
If your reaction is:   metal + molecule --> insulator

you need probably   MANY k-points for the metal,
                     1 k-point for the molecule (in a big supercell)
                     few k-points for the insulator.

In addition, not the   "total number of k-points in the BZ"   is important, but its
"density in reciprocal space". I.e. if one of the reactants has only one atom/cell
(and thus a very BIG reciprocal cell), but another reactant has a very big unitcell,
you should consider this in your k-mesh and use a large and small number of k-points,
respectively.
The number of "special k-points" is NEVER really important, since this may change
drastically with symmetry.

Che Franklin N. schrieb:
> Dear fellow users,
> 
> I am a new Wien user and I've got a very general question: I am calculating reaction
> enthalpies and I read somewhere that when calculating the energies of reactants and
> products, the number of k points should be the same for all of them in order to be
> comparable. Does this refer to the total number of k points in the BZ or the special k
> points generated? 
> Thanks in advance for your help.
> 
> 
>  Che Franklin N.
>  Chem Graduate Student
>  UNBF, Canada
> 
> 
> 
> 
> 
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-- 

                                       P.Blaha
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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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