Crystallographic Database - Overview

Overview

Crystallographic data are primarily extracted from published scientific articles and supplementary material. Newer versions of crystallographic databases are built on the relational database model, which enables efficient cross-referencing of tables. Cross-referencing serves to derive additional data or enhance the search capacity of the database.

Data exchange among crystallographic databases, structure visualization software, and structure refinement programs has been facilitated by the emergence of the Crystallographic Information File (CIF) format. The CIF format is the standard text file format for the exchange and archiving of crystallographic data. It was adopted by the International Union of Crystallography (IUCr), who also provides full specifications of the format. It is supported by all major crystallographic databases.

The increasing automation of the crystal structure determination process has resulted in ever higher publishing rates of new crystal structures and, consequentially, new publishing models. Minimalistic articles contain only crystal structure tables, structure images, and, possibly, abstract-like structure description. They tend to be published in author-financed or subsidized open-access journals. Acta Crystallographica Section E and Zeitschrift für Kristallographie belong in this category. More elaborate contributions may go to traditional subscriber-financed journals. Hybrid journals, on the other hand, embed individual author-financed open-access articles among subscriber-financed ones. Publishers may also make scientific articles available online, as Portable Document Format (PDF) files.

Crystal structure data in CIF format are linked to scientific articles as supplementary material. CIFs may be accessible directly from the publisher’s website, crystallographic databases, or both. In recent years, many publishers of crystallographic journals have come to interpret CIFs as formatted versions of open data, i.e. representing non-copyrightable facts, and therefore tend to make them freely available online, independent of the accessibility status of linked scientific articles.