[Pw_forum] Conserving the same Wyckoff multiplicity in the input and in the output

[Paolo Giannozzi]

This is what you get:
      2 Sym. Ops., with inversion, found
          (note:  2 additional sym.ops. were found but ignored
           their fractional translations are incommensurate with FFT grid)
and this is what you get if you specify "use_all_frac=.true.":
      4 Sym. Ops., with inversion, found ( 2 have fractional translation)
These are symmetry operations (visible with verbosity='high')
                                    s                        frac. trans.

      isym =  1     identity

 cryst.   s( 1) = (     1          0          0      )
                  (     0          1          0      )
                  (     0          0          1      )

 cart.    s( 1) = (  1.0000000  0.0000000  0.0000000 )
                  (  0.0000000  1.0000000  0.0000000 )
                  (  0.0000000  0.0000000  1.0000000 )


      isym =  2     180 deg rotation - cart. axis [0,0,1]

 cryst.   s( 2) = (    -1          0          0      )    f =(  0.0000000 )
                  (     0         -1          0      )       (  0.5000000 )
                  (     0          0          1      )       (  0.5000000 )

 cart.    s( 2) = ( -1.0000000  0.0000000  0.0000000 )    f =(  0.0000000 )
                  (  0.0000000 -1.0000000  0.0000000 )       (  0.2688348 )
                  (  0.0000000  0.0000000  1.0000000 )       (  0.3657871 )


      isym =  3     inversion

 cryst.   s( 3) = (    -1          0          0      )
                  (     0         -1          0      )
                  (     0          0         -1      )

 cart.    s( 3) = ( -1.0000000  0.0000000  0.0000000 )
                  (  0.0000000 -1.0000000  0.0000000 )
                  (  0.0000000  0.0000000 -1.0000000 )


      isym =  4     inv. 180 deg rotation - cart. axis [0,0,1]

 cryst.   s( 4) = (     1          0          0      )    f =(  0.0000000 )
                  (     0          1          0      )       (  0.5000000 )
                  (     0          0         -1      )       (  0.5000000 )

 cart.    s( 4) = (  1.0000000  0.0000000  0.0000000 )    f =(  0.0000000 )
                  (  0.0000000  1.0000000  0.0000000 )       (  0.2688348 )
                  (  0.0000000  0.0000000 -1.0000000 )       (  0.3657871 )


     point group C_2h (2/m)
     there are  4 classes
     the character table:

       E     C2    i     s_h
A_g    1.00  1.00  1.00  1.00
B_g    1.00 -1.00  1.00 -1.00
A_u    1.00  1.00 -1.00 -1.00
B_u    1.00 -1.00 -1.00  1.00

     the symmetry operations in each class and the name of the first element:

     E        1
          identity
     C2       2
          180 deg rotation - cart. axis [0,0,1]
     i        3
          inversion
     s_h      4
          inv. 180 deg rotation - cart. axis [0,0,1]

On Wed, Apr 5, 2017 at 7:51 AM, Paolo Giannozzi <p.giannozzi at gmail.com> wrote:
> Structural optimization doesn't break the symmetry. The final symmetry
> - the one found by the code, I mean - should be  the same as the
> initial one.
>
> On Wed, Apr 5, 2017 at 2:46 AM, hqtst42 <hqtst42 at netc.pl> wrote:
>> In the input file, there are the atomic coordinates for only one
>> molecule, and with the symmetry operation, I expect 4 equivalent
>> molecules per unit cell. Yet, the structure optimisation results in 2
>> pairs of 2 equivalent molecules per unit cell. I would like to explain
>> to the program not to break the symmetry.
>>
>> Le 2017/04/04 à 21:45, Paolo Giannozzi a écrit :
>>> What do you mean by "results with multiplicity 1" and "Wyckoff multiplicity?
>>>
>>> On Tue, Apr 4, 2017 at 12:08 PM, hqtst42 <hqtst42 at netc.pl> wrote:
>>>> Dear everyone,
>>>>
>>>> In the enclosed input file, I set atomic coordinates of all equivalent atoms
>>>> with crystal_sg and the space group.
>>>>
>>>> This should give results with a multiplicity of 1, but I have instead a
>>>> multiplicity of 2 in the output file.
>>>> How can I force the program to conserve the Wyckoff multiplicity taken as an
>>>> input ?
>>>> All in QE v 6.0
>>>>
>>>> Many thanks in advance,
>>>>
>>>> Henri Colaux
>>>> Research associate
>>>> RIKEN Yokohama
>>>>
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>>>
>>
>>
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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



-- 
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