[Wien] Symmetry in SG Fm3c

[Caroline Röhr]

dear WIEN users + programmers

in the cubic spacegroup Fm3c there seem to be some
inconsistencies in the symmetry-operations (SO)
seen by comparison of the ones generated 
with those listed in the International Tables (IT)

the struct-file (generated by structgen) contains:

*******      *.struct   ********************

.....
  48      NUMBER OF SYMMETRY OPERATIONS
 1 0 0 0.0000000
 0-1 0 0.0000000
 0 0-1 0.0000000
       1
.....

*** .... and up to SO no. 24 everything is ok.
   after that, all SO are encoded by using
   0.5 0.5 0.5 (=0, 0, 0.5) or directly 0, 0, 0.5
   as additional translation vector. if one compares
   with the IT, it can be easily seen, that in
   SO 30 (=43 in IT), SO 36 (=44 in IT), SO 40 (=42 in IT)
   SO 45 (=41 in IT), SO 47 (=45 in IT) and SO 48 (=40 in IT)
   the translational vector should also be one of the
   two listed above and not (0.5 0. 0.) or (0. 0.5 0.)

**************************************************
** in *.struct         **** should be:

 0 0-1 0.5000000
 0-1 0 0.5000000
 1 0 0 0.5000000
      25
 0 0 1 0.0000000
 0 1 0 0.0000000
-1 0 0 0.5000000
      26
 0-1 0 0.5000000
-1 0 0 0.5000000
 0 0-1 0.5000000
      27
 0 0 1 0.5000000
 0 1 0 0.5000000
 1 0 0 0.5000000
      28
 0-1 0 0.5000000
 1 0 0 0.5000000
 0 0-1 0.5000000
      29
 1 0 0 0.0000000       0.00000  or  0.50000
 0 0-1 0.5000000       0.00000      0.50000
 0 1 0 0.0000000       0.50000      0.50000
      30
-1 0 0 0.5000000
 0 0-1 0.5000000
 0 1 0 0.5000000
      31
 0 1 0 0.0000000
 1 0 0 0.0000000
 0 0-1 0.5000000
      32
-1 0 0 0.5000000
 0 0-1 0.5000000
 0-1 0 0.5000000
      33
 0 1 0 0.5000000
-1 0 0 0.5000000
 0 0-1 0.5000000
      34
 0 0 1 0.5000000
 0-1 0 0.5000000
-1 0 0 0.5000000
      35
 0 1 0 0.0000000        s. above
-1 0 0 0.5000000  
 0 0 1 0.0000000
      36
 0 1 0 0.5000000
 1 0 0 0.5000000
 0 0 1 0.5000000
      37
 0 0-1 0.5000000
 0 1 0 0.5000000
-1 0 0 0.5000000
      38
 1 0 0 0.0000000
 0 0 1 0.0000000
 0-1 0 0.5000000
      39
 0 0-1 0.5000000
 0 1 0 0.0000000         s. above
 1 0 0 0.0000000
      40
-1 0 0 0.5000000
 0 0 1 0.5000000
 0-1 0 0.5000000
      41
 1 0 0 0.5000000
 0 0-1 0.5000000
 0-1 0 0.5000000
      42
 0-1 0 0.5000000
-1 0 0 0.5000000
 0 0 1 0.5000000
      43
 0 0-1 0.5000000
 0-1 0 0.5000000
-1 0 0 0.5000000
      44
 0-1 0 0.5000000
 1 0 0 0.0000000        s. above
 0 0 1 0.0000000
      45
 1 0 0 0.5000000
 0 0 1 0.5000000
 0 1 0 0.5000000
      46
 0 0 1 0.0000000
 0-1 0 0.5000000          s. above
 1 0 0 0.0000000
      47
-1 0 0 0.5000000       s. above
 0 0 1 0.0000000
 0 1 0 0.0000000
      48
*****************************

because of many special positions, the error can only
be seen (in our case) when running the AIM-program,
which checkes the symmetry and comes up with:

*** *.outputaim:  *****
 NO SYMMETRY OPERATION FOUND IN ROTDEF
           2           5
  0.750000000000000       0.750000000000000       0.750000000000000     
  0.680161000000000       0.119128000000000       0.500000000000000    

*******************

with kind regards

caroline.



-------------------------------------------------
Caroline R"ohr, Freiburg, Germany
caroline at ruby.chemie.uni-freiburg.de
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