The program PSEUDO 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 defined cell multiplication
- 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)
Finally, the program needs a maximum allowed tolerance for pseudosymmetry calculations, i.e., the maximal allowed displacement (in Angstroms) between the mapped atoms of the low symmetry structure obtained by applying the coset representatives of the supergroup with respect to the subgroup (for details, please refer to the article referenced below). Normally a default value of 2Å is a good choice.
When you have filled all of the data, click on the [Show] button to search for pseudosymmetry with respect to the chosen supergroups option.
To get a tutorial about this program click here.
If you are using this program in the preparation of a paper, please cite it in the following form:
C. Capillas, E.S. Tasci, G. de la Flor, D. Orobengoa, J.M. Perez-Mato and M.I. Aroyo. "A new computer tool at the Bilbao Crystallographic Server to detect and characterize pseudosymmetry". Z. Krist. (2011), 226(2), 186-196 DOI:10.1524/zkri.2011.1321.
If you are interested in other publications related to Bilbao Crystallographic Server, click
here.
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Please, enter structure data in the text area (or load CIF file).
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We are developing a new version of PSEUDO. It is currently in beta version and it will be available soon. Please, let us know if you experience any problem with the program or you find errors. The e-mail for contact is cryst@wm.lc.ehu.es. Any comments and/or critics are welcome, too!.
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Select supergroups type for pseudosymmetry search.
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[*] Only for triclinics and monoclinics.
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Enter the tolerance (maximum allowed distance) for pseudosymmetry search.
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Pseudosymmetry search