Bilbao Crystallographic Server => Pseudosymmetry search Help

Degree of Pseudosymmetry Estimation


Pseudosymmetry search
The program DOPE looks for a pseudosymmetry in a structure among the (minimal) supergroups of the structure's space group.

The first step in the program is the input of the structure's data. The data can be given using the form or it can be loaded from a CIF file. The necessary data for the structure consists in the number of its space group in the International Tables for Crystallography, Vol A, the lattice parameters (in A and degrees), the number of the atoms in the asymmetric unit and the corresponding atomic positions. Then, it's necessary to select among what type of supergroups the search is performed. The available options are:
  • Minimal supergroups
  • Supergroups for a given Space group and index
  • Supergroup for a well-known transformation matrix
Another option (only for triclinic and monoclinic groups) is to check first the pseudosymmetry of the given cell (obtaining the possible lattice transformations for a given angular tolerance and checking if they are compatible with a space supergroup transformation).

When you have filled all of the data, click on the [Show] button to search for pseudosymmetry with respect to the chosen supergroups option.

NOTE: The program only accepts, as input data, structures described in a standard/default setting of the space group. If the original structure is described with respect to an ITA setting, the program SETSTRU can be used to transform it to the standard setting. In the case of more arbitrary non-conventional settings, the tool TRANSTRU can be of some help, if the transformation to the standard setting is known.



If you are using this program in the preparation of a paper, please cite in in the following form:

"C. Capillas, M.I. Aroyo and J.M. Perez-Mato."Methods for pseudosymmetry evaluation: a comparison between the atomic displacements and electron density approaches".Z. Krist. 220, 691-699 (2005).
Please, enter structure data in the text area (or load CIF file).


Formulae

Structure data
[in CIF format]

HINT: [ The option for a given filename is preferential ]
HINT: [ ATOM ] [ ID ] [ WP ] [X] [Y] [Z] [OCC] [Biso] [SCAT]
Initial Structure (LS)

Select supergroups type for pseudosymmetry search.

1. Minimal supergroups [Show only indices in supergroups table]
2. Supergroups with k-index ik:
3. Specify supergroup transformation G:
Transf. Matrix
(in option 2 only)
Linear part
Origin Shift
4. [*] Lattice Pseudosymmetry with minimal supergroups Ang. Tol (in degrees)
[*] Only for triclinics and monoclinics.


[ Bilbao Crystallographic Server Main Menu ]

Bilbao Crystallographic Server
http://www.cryst.ehu.es
For comments, please mail to
cryst@wm.lc.ehu.es