[Pw_forum] uniform k-point grid with option 'automatic'??

[Paolo Giannozzi]

If you cannot use the automatic grid as provided by the "automatic"
option of the K_POINTS card, you can use an auxiliary program
"PW/tools/kpoints.x" to produce a uniform grid of k-points in the 
complete Brillouin Zone.

P.
On Fri, 2015-04-24 at 17:25 +0200, Ludwig, Stephan wrote:

>         
>         
>         
>         I have a question concerning the option 'automatic' for
>         k_point card:
>         
>         
>         In order to use the epsilon.x postprocessing tool I need a
>         uniform k-point grid. In the manual for epsilon.x
>         (http://web.mit.edu/espresso_v5.0.1/i386_linux26/espresso-5.0.1/PP/Doc/eps_man.pdf)
>         
>         
>         it is said that the option automatic is not suitable:
>         
>         
>         
>         Epsilon.x doesn’t support the reduction of the k-points grid
>         into the unreducible Brillouin zone, so the previous PW runs
>         must be performed with a uniform k-points grid and all
>         k-points weights
>         
>         must be equal to each other, i.e. in the k-points card the
>         k-points coordinates must be given manually in crystal or alat
>         or bohr , but not with the automatic option.
>         
>         
>         
>         
>         On the other hand I read in the pw_user_guide
>         (http://www.quantum-espresso.org/wp-content/uploads/Doc/pw_user_guide.pdf)  that in order to obtain a uniform k-point grid I shall use the option automatic:
>         
>         
>         
>          In the latter case, you should specify a uniform grid of
>         points. For DOS calculations you should
>         chooseoccupations='tetrahedra' together with an automatically
>         generated uniform k-point grid (card KPOINTS with option
>         \automatic").
>         
>         So what is the truth?
>         
>         
>         
>         Thanks and regards
>         
>         
>         
>         Stephan Ludwig
>         
>         
>           
>         
>         
>         
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222