Bärnighausen Trees – A group–subgroup reference database

Group–subgroup schemes are a useful tool in crystal chemistry for systemizing crystal structures and they are an indispensable help during X-ray crystallographic studies of complex, twinned and modulated structures. Meanwhile many superstructure variants are summarized within so-called Bärnighausen trees. The present database lists relevant literature with respect to the crystallographic/group-theoretical tools and original work and gives a tabulated overview on the crystallographic fingerprints (aristotype, space group symbol, Pearson code and Wyckoff sequence) of the respective superstructures.