Bilbao Crystallographic Server Help

Twins Domains

The program calculates the Raman or Hyper-Raman tensors and the expresion for the intensity for each one orientation domain. Given the high and low symmetry structure and the transformation matrix which relates both structures the program calculates the cosets decomposition between the group and the subgroup and it identifies which are the orientational domains in the decomposition. Once the programs has the orientational cosets representatives it transform the tensor (Raman or Hyper-Raman) taking the cosets representatives as the transformation matrix. From the transform tensor it calculates the expressions for the intensity.

Input

One have to introduce the following information in the program:
The high and low symmetry structures can be introduced directly or in CIF format file. If you do not know the matrix which relates both structures you can use the program STRUCTURE RELATIONS which will give you the matrix you are looking for. One can introduce the transformation matrix form or in abc form.


Output:

In the first part of the output one can find the information that has been introduced and the information abut the Raman activity for each one of the structures:



After the information about the input one can find the information about the domains which contains the cosets decomposition between the high and low space groups:



Using each one of the cosets representatives it is transform the raman tensor and the is a direct link to the intensity expressions. In this case there are two twin domains, one of the cosets representatives is the identity so the Raman tensor remains the same. The other coset representative is b,-a,c, using this cosets as transformation matrix the tensor transforms as:



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