|Bilbao Crystallographic Server Structure Utilities Help COMPSTRU|
Often a quantitative comparison of two structural models of the same phase, coming from different sources, is difficult because the models, although postulating the same space group symmetry, are described using different sets of atoms in the asymmetric unit, or different equivalent choices of origin or cell orientations. The program COMPSTRU compares two structure descriptions of the same compound characterizing the similarity of the two structure models by different quantitative descriptors.
First, the program transforms the Structure 2 to the most similar configuration of Structure 1. The difference between the two models is quantified by evaluation of (i) the global distortion decomposed into a spontaneous strain (lattice deformation) and atomic displacement field representing the distances between the pared atoms of the two structures; (ii) the measure of similarity as introduced by Bergerhoff (Bergerhoff et al., 1999).
The determination of the transformation matrix that transforms Structure 2 to the most similar configuration to Structure 1 is done in two steps:
The initial structures should be described with respect to the standard (default) settings of the structure space group. If transformation of the structures into standard settings is necessary, then the program SETSTRU on this server can be used.
The program is also helpful for the recognition of similar atomic arrangements of different compounds that is essential for the classification of crystal structures into isoconfigurational structure types.
Bilbao Crystallographic Server
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