[cctbxbb] Obtaining symmetry information

[Peter Zwart]

If you just want to obtain the xray.structure object in P1, you can use 
the command .expand_to_p1():

----------------------------------------------------------
from cctbx.development import random_structure
from cctbx import sgtbx
from libtbx import easy_pickle
import sys

def tst(space_group_info, n_elements=10, d_min=1.5):
   # make a random structure
   structure = random_structure.xray_structure(
     space_group_info,
     elements=["Si"]*n_elements,
     volume_per_atom=1000,
     min_distance=3.,
     general_positions_only=False)
   # show me!
   structure.show_summary().show_scatterers()
   # fill the whol unit cell and throw away the symmetry info
   new_structure = structure.expand_to_p1()
   # show me again!
   new_structure.show_summary().show_scatterers()

def run():
   tst(sgtbx.space_group_info(sys.argv[1]))

if (__name__ == "__main__"):
   run()

----------------------------------------------------------

HTH

Peter


Petrus H Zwart wrote:
>> Dear All,
>>
>> I am trying to reconstruct an entire unit cell from an  
>> cctbx.xray.structure object that contains the scatterers in the  
>> asymmetric unit. Ideally, I'd call a method that does the work for  
>> me, but at least I would like to obtain a list of the symmetry  
>> transformations that must be applied. That information must be  
>> somewhere in there... but where?
>>
>> Konrad.
> 
> An cctbx.xray.structure object has a method called space_group() I believe.
> Check out this example:
> http://phenix-online.org/cctbx_sources/cctbx/cctbx/examples/space_group_matrices.py
> 
> ( $CCTBX_DIST/cctbx/examples/space_group_matrices.py )
> 
> to get an idea where things are.
> 
> You can also try other examples in that directory and of course
> libtbx.help cctbx.sgtbx.space_group
> 
> gives you some clue of what might be where.
> 
> HTH
> 
> Peter
> 
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