OU Crystallography Lab

Department of Chemistry & Biochemistry
Chemical Crystallography Laboratory

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Evaluating a Crystal Structure

The IUCr has developed a format for communicating information about a crystal structure using Crystallographic Information File. These guidelines direct the user to ways of evaluating the correctness and quality of a crystal structure report. The user must remember that the precision of results is at best a fuzzy concept with generally no sharp dividing lines. The International Union of Crystallography does have a list of criteria for acceptance of crystal structure reports to the journal Acta Crystallographica C. These acceptance criteria are being used by nearly all journals for identifying problem areas in small molecule crystal structures. All small molecule crystal structures should be validated using the checkcif program.

A report evaluating the crystal structure in a given CIF will be returned to the sender.

Tables of data as a pdf document may be prepared by submitting a cif via the printcif web page. Be sure to select the type of output; usually this should be pdf file.

Several validation suites for macromolecular crystal structures have been developed. These include software from the Protein Data Bank server, the Joint Center for Structural Genomics, and the UCLA server.

The general criteria used to evaluate small-molecule crystal structures are as follows:

μ × mid dim Correction type
> 3.0 Analytical required
> 1.0 Analytical recommended
> 0.1 Some correction required
< 0.1 None required
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