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Match! using ICSD/Retrieve and free-of-charge reference data

Since Match! version 1.8, the software can use the ICSD/Retrieve database (release 1993-2002) as source of reference diffraction patterns, if you have a valid licence for this database. All entries imported from ICSD/Retrieve contain atomic coordinates, based on which the corresponding powder diffraction patterns are calculated automatically during the import process. Besides this, for all entries I/Ic-values are calculated, so that a semi-quantitative analysis can be performed.

By combining a reference database imported from ICSD/Retrieve (which typically contains "older" entries) with the free-of-charge COD reference database (which basically contains more recent entries, see below), you will get a real alternative to the PDF database at low price!

Since version 1.7, Match! is not only able to use any ICDD PDF database product (as with all previous versions), but also to use free-of-charge reference patterns calculated from crystal structure data that are available free-of-charge in the COD ("Crystallography Open Database").

In this context, we would like to thank Pete Strickland (IUCr), Armel Le Bail (COD) and Bob Downs (AMCSD) for their kind permission to download and distribute their data free-of-charge!

The COD reference database (which also contains entries from IUCr journals and the AMCSD ("American Mineralogist Crystal Structure Database")) currently provides more than 94,000 entries. All entries contain atomic coordinates, based on which the corresponding powder diffraction patterns have been calculated. Besides this, for all entries, I/Ic-values have been calculated, so that a semi-quantitative analysis can be performed. Updates of the free-of-charge reference databases will become available for download from time to time.

Along with the optional usage of COD reference data, the general handling of reference databases has been significantly improved: You can switch between different reference databases (e.g. PDF-4+ and PDF-4 Organics or PDF-2 and COD) while your sample diffraction pattern is still in memory, so you can easily compare resulting entries/phases based on one or the other reference database. Of course, when switching, there is no need for a time-consuming re-indexation of the reference databases!

Please click here to go to the update page, and download the update to latest version of Match! Note that the update (or online update) does not install any reference database! If you would like to install one of the free-of-charge reference pattern databases, you have to download and install them separately after you have installed the update to the new Match! version!

We have run several tests in order to evaluate the quality of the various reference databases mentioned above:

Compared to using the classical ICDD PDF database, our tests reveal a somewhat diverse performace when using the free-of-charge COD reference patterns: When mineral samples were investigated, the results were generally very good, thanks to the excellent coverage of the AMCSD subsection of the COD. Even for many samples other than minerals, the correct phases were identified in most cases, however, we found some (few) samples where main phases were not recognized because the corresponding reference patterns were not present in the COD reference database. In all cases, it was no problem to identify all phases when using the ICDD PDF-2 Release 2007 database.

According to our experience, it is optimal to combine the COD database (which basically contains more recent entries) with a user database created from ICSD/Retrieve (which typically contains "older" entries). Using such a combined reference database is the best solution if you do not have a recent ICDD PDF database available!