The STARANISO Server
Anisotropy of the Diffraction Limit
If you have some results that illustrate some beneficial effect of using the server on your data, and that you are happy to share with the community, please email the contact address at the bottom of the page.
A fourth type of interactive colour-coded reciprocal-lattice display has been added when the input data are given as an unmerged XDS_ASCII.HKL file (not MTZ format).  The left-most scene then shows the value of the CORR statistic produced by XDS (item 11 in the file), i.e. for each reflection, the correlation coefficient between the observed reflection profile and the predicted profile that was used to integrate it.
The profile correlation plot gives a primary diagnostic of problems at the integration stage, as a mismatch of profiles could result from shortcomings in the sample (e.g. a cracked crystal) or in the profile estimation method (e.g. too coarse a partitioning of the detector surface).  As the profile correlation is given on a per-reflection basis, it is a more sensitive indication of such problems than the loss in <I /σ(I)> that it causes, since the latter quantity is a local average.
This development is in line with our philosophy of making as few prior assumptions as possible about the data (motto: "Let the data speak!").
Implicit assumptions made (incorrectly) by some software - namely that the anisotropic diffraction-limit surface is ellipsoidal with principal axes either parallel to the crystal axes or to the principal axes of the anisotropy tensor ellipsoid - were already relaxed in the previous version of the server, through a complete separation of the rôles of the anisotropic diffraction limit and of the anisotropy tensor.
With this new development of a protocol for anisotropy correction at the unmerged data stage, we go further.  By applying the anisotropic diffraction cut-off at an earlier stage in processing to the unmerged data, we try to ensure that weak measurements that can impact the quality of the final data by biasing the image scales and the error model can be eliminated early on in the process.
Either link to a saved bookmark, or enter here the 10- or 16-character job ID that was assigned on submission:
|Ian J. Tickle*||Andrew Sharff|
|Claus Flensburg||Oliver Smart|
|Peter Keller||Clemens Vonrhein|
|Wlodek Paciorek||Gérard Bricogne|