# [Pw_forum] repeated k-points in a phonon calculation

stefano de gironcoli degironc at sissa.it
Tue Jul 12 19:22:56 CEST 2016

```for a phonon calculation at a given q vector the PHONON code needs
wavefunctions at a set of k and at the corresponding k+q... the former
are used to sample the BZ (they have a weight associated to them) the
latter are used to orthogonalize the perturbed wavefunction to the
valence band (no need of a weight for them).
Even if some of the k and k+q coincide it's simpler to recalculate them.
compared to all the rest their cost is negligible.

stefano

On 12/07/2016 19:15, Eduardo Menendez wrote:
> Dear fellows,
> I would like to know if it is normal to have reapeated k-points in a
> phonon calculation with PHONON code, or if it other wise a problem
> with my compilation.
> I see duplicated k-points in the list, and I also see many points with
> zero weight.
> For example, points 1 and 28 are the same, one with weight, and the
> other with 0 weigh.  point 2 is repeated at 53, etc.  The k-points
> grid was defined as
>  automatic  3 3 3 1 1 1
>
>      Calculation of q =    0.3333333   0.3333333 -0.3333333
> ......
>      number of k points=    54  Methfessel-Paxton smearing, width
> (Ry)=  0.0073
>                        cart. coord. in units 2pi/alat
>         k(    1) = (   0.1666667   0.1666667   0.1666667), wk =
> 0.0740741
>         k(    2) = (   0.5000000   0.5000000  -0.1666667), wk =
> 0.0000000
>         k(    3) = (   0.1666667   0.1666667  -0.5000000), wk =
> 0.0740741
>         k(    4) = (   0.5000000   0.5000000  -0.8333333), wk =
> 0.0000000
>         k(    5) = (   0.1666667  -0.5000000  -0.5000000), wk =
> 0.0740741
>         k(    6) = (   0.5000000  -0.1666667  -0.8333333), wk =
> 0.0000000
>         k(    7) = (  -0.5000000  -0.5000000  -0.5000000), wk =
> 0.0740741
>         k(    8) = (  -0.1666667  -0.1666667  -0.8333333), wk =
> 0.0000000
>         k(    9) = (  -0.1666667   0.1666667   0.1666667), wk =
> 0.0740741
>         k(   10) = (   0.1666667   0.5000000  -0.1666667), wk =
> 0.0000000
>         k(   11) = (  -0.1666667   0.1666667  -0.1666667), wk =
> 0.0740741
>         k(   12) = (   0.1666667   0.5000000  -0.5000000), wk =
> 0.0000000
>         k(   13) = (   0.1666667  -0.1666667  -0.1666667), wk =
> 0.0740741
>         k(   14) = (   0.5000000   0.1666667  -0.5000000), wk =
> 0.0000000
>         k(   15) = (   0.1666667   0.1666667  -0.1666667), wk =
> 0.0740741
>         k(   16) = (   0.5000000   0.5000000  -0.5000000), wk =
> 0.0000000
>         k(   17) = (  -0.1666667  -0.1666667  -0.1666667), wk =
> 0.0740741
>         k(   18) = (   0.1666667   0.1666667  -0.5000000), wk =
> 0.0000000
>         k(   19) = (   0.1666667  -0.1666667   0.1666667), wk =
> 0.0740741
>         k(   20) = (   0.5000000   0.1666667  -0.1666667), wk =
> 0.0000000
>         k(   21) = (  -0.1666667  -0.1666667   0.1666667), wk =
> 0.0740741
>         k(   22) = (   0.1666667   0.1666667  -0.1666667), wk =
> 0.0000000
>         k(   23) = (  -0.1666667   0.1666667  -0.5000000), wk =
> 0.0740741
>         k(   24) = (   0.1666667   0.5000000  -0.8333333), wk =
> 0.0000000
>         k(   25) = (   0.1666667  -0.1666667   0.5000000), wk =
> 0.0740741
>         k(   26) = (   0.5000000   0.1666667   0.1666667), wk =
> 0.0000000
>         k(   27) = (  -0.1666667  -0.1666667   0.5000000), wk =
> 0.0740741
>         k(   28) = (   0.1666667   0.1666667   0.1666667), wk =
> 0.0000000
>         k(   29) = (  -0.5000000  -0.1666667   0.1666667), wk =
> 0.0740741
>         k(   30) = (  -0.1666667   0.1666667  -0.1666667), wk =
> 0.0000000
>         k(   31) = (   0.5000000  -0.1666667  -0.1666667), wk =
> 0.0740741
>         k(   32) = (   0.8333333   0.1666667  -0.5000000), wk =
> 0.0000000
>         k(   32) = (   0.8333333   0.1666667  -0.5000000), wk =
> 0.0000000
>         k(   33) = (  -0.5000000   0.1666667  -0.1666667), wk =
> 0.0740741
>         k(   34) = (  -0.1666667   0.5000000  -0.5000000), wk =
> 0.0000000
>         k(   35) = (   0.5000000   0.1666667   0.1666667), wk =
> 0.0740741
>         k(   36) = (   0.8333333   0.5000000  -0.1666667), wk =
> 0.0000000
>         k(   37) = (  -0.1666667  -0.5000000   0.1666667), wk =
> 0.0740741
>         k(   38) = (   0.1666667  -0.1666667  -0.1666667), wk =
> 0.0000000
>         k(   39) = (  -0.1666667   0.5000000  -0.1666667), wk =
> 0.0740741
>         k(   40) = (   0.1666667   0.8333333  -0.5000000), wk =
> 0.0000000
>         k(   41) = (   0.1666667  -0.5000000  -0.1666667), wk =
> 0.0740741
>         k(   42) = (   0.5000000  -0.1666667  -0.5000000), wk =
> 0.0000000
>         k(   43) = (   0.1666667   0.5000000   0.1666667), wk =
> 0.0740741
>         k(   44) = (   0.5000000   0.8333333  -0.1666667), wk =
> 0.0000000
>         k(   45) = (  -0.1666667  -0.5000000  -0.5000000), wk =
> 0.0740741
>         k(   46) = (   0.1666667  -0.1666667  -0.8333333), wk =
> 0.0000000
>         k(   47) = (  -0.5000000   0.1666667   0.5000000), wk =
> 0.0740741
>         k(   48) = (  -0.1666667   0.5000000   0.1666667), wk =
> 0.0000000
>         k(   49) = (   0.5000000  -0.1666667   0.5000000), wk =
> 0.0740741
>         k(   50) = (   0.8333333   0.1666667   0.1666667), wk =
> 0.0000000
>         k(   51) = (  -0.5000000   0.5000000   0.1666667), wk =
> 0.0740741
>         k(   52) = (  -0.1666667   0.8333333  -0.1666667), wk =
> 0.0000000
>         k(   53) = (   0.5000000   0.5000000  -0.1666667), wk =
> 0.0740741
>         k(   54) = (   0.8333333   0.8333333  -0.5000000), wk =
> 0.0000000
>
> Thank you
>
> Eduardo Menendez Proupin
> URL: http://www.gnm.cl/emenendez
>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum

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