[QE-users] Symmetry Considerations

[Paolo Giannozzi]

On Thu, Jan 10, 2019 at 4:30 PM Offermans Willem <willem.offermans at vito.be>
wrote:

     2 Sym. Ops., with inversion, found ( 1 have fractional translation)
> [...] What does it mean?
>

it means that the symmetry operation consists in a rotation (or a rotation
+ spatial inversion) plus a translation (not a lattice one)

At some point in the sequence of calculations, the output contained the
> following message about symmetry:
>
>     No symmetry found
>
> I was surprised about the lost of symmetry. Is it related to the
> fractional translation?
>

no, unless this happens in the last scf step, in which the FFT grid may
change, in which case this is what may happen:

          (note:  1 additional sym.ops. were found but ignored
           their fractional translations are incommensurate with FFT grid)
Paolo
-- 
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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