[Pw_forum] How to set variables when get symmetry operation # N not allowed?

[Paolo Giannozzi]

Set variable "use_all_frac=.true." and option "verbosity='high'". This will
find and print all symmetries and associated fractional translations. If a
fractional translation along a crystal axis is 1/n, with n integer, the FFT
dimension along that axis must contain a factor n. If you do not need
hybrid functionals or phonons, just set variable "use_all_frac=.true."

Paolo

On Wed, Feb 7, 2018 at 8:18 PM, Arena Konta <qe6user at gmail.com> wrote:

> Hi All,
>
> I read Troubleshooting and found out that "you can force your FFT grid to be commensurate with fractional translation (set variables nr1, nr2, nr3 to suitable values)". How to do this for the crystal structure presented below? I have tried to this for various k-mesh, but every time I get 6 symmetry operations are not compatible with FFT grid:
>  warning: symmetry operation # 2 not compatible with FFT grid.
>   -1 0 0
>    0 -1 0
>   -1 -1 1
>      warning: symmetry operation # 3 not compatible with FFT grid.
>    0 -1 0
>    1 0 0
>    0 -1 1
>      warning: symmetry operation # 4 not compatible with FFT grid.
>    0 1 0
>   -1 0 0
>   -1 0 1
>      warning: symmetry operation # 6 not compatible with FFT grid.
>    1 0 0
>    0 1 0
>    1 1 -1
>      warning: symmetry operation # 7 not compatible with FFT grid.
>    0 1 0
>   -1 0 0
>    0 1 -1
>      warning: symmetry operation # 8 not compatible with FFT grid.
>    0 -1 0
>    1 0 0
>    1 0 -1
>
> &SYSTEM
>   ibrav = 0
>   celldm(1) = 18.61847
>   nat = 9
>   ntyp = 2
> /
> CELL_PARAMETERS {alat}
>   1.000000000000000 0.000000000000000 0.000000000000000
>   0.000000000000000 1.000000000000000 0.000000000000000
>   0.500000000000000 0.500000000000000 0.175193124160743
>
> ATOMIC_POSITIONS {crystal}
> A 0.304370000000000 0.373120000000000 0.000000000000000
> A 0.626880000000000 0.304370000000000 0.000000000000000
> A 0.695630000000000 0.626880000000000 0.000000000000000
> A 0.373120000000000 0.695630000000000 0.000000000000000
> A 0.000000000000000 0.000000000000000 0.000000000000000
> B 0.055910000000000 0.282920000000000 0.000000000000000
> B 0.717080000000000 0.055910000000000 0.000000000000000
> B 0.944090000000000 0.717080000000000 0.000000000000000
> B 0.282920000000000 0.944090000000000 0.000000000000000
>
> K_POINTS automatic
> 10 10 18 0 0 0
>
>
>
> --
> with regards
>
> Arena Konta
> The Institute of Thermophysics in Novosibirsk Scientific Center
>
>
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>



-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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