A superb program for chemical crystal structures. To use Mercury you need a CIF or MOL file containing the measured crystal stucture of a certain chemical solid. There are no universal CIF/MOL collections freely available, but for a start try finding TGZ-zipped teaching_subset_cifs.tgz file from the CCDC web site. (= the author of this program) Even better if you get real ORTEP structure cifs from the web sites of real chemistry journals.
akhilesh kumar
