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Revision as of 16:49, 15 February 2015
, 16:49, 15 February 2015→Space group selected by XDS: ambiguous with respect to enantiomorph and screw axes
In case of a crystal with an unknown space group (SPACE_GROUP_NUMBER=0 in [[XDS.INP]]), XDS (since [http://www.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/Release_Notes.html version June 2008]) helps the user in determination of the correct space group, by suggesting possible space groups compatible with the lattice symmetry of the data, and by calculating the R<sub>meas</sub> for these space groups.
In case of a crystal with an unknown space group (SPACE_GROUP_NUMBER=0 in [[XDS.INP]]), XDS (since [http://www.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/Release_Notes.html version June 2008]) helps the user in determination of the correct space group, by suggesting possible space groups compatible with the lattice symmetry of the data, and by calculating the R<sub>meas</sub> for these space groups.
XDS (or rather, the CORRECT step) makes an attempt to pick the correct space group automatically: it chooses that space group which has the highest symmetry (thus yielding the lowest number of unique reflections) and still a tolerable R<sub>meas</sub> compared to the R<sub>meas</sub> the data have in any space group (which is most likely a low-symmetry space group - often P1).
XDS (or rather, the [[CORRECT.LP|CORRECT]] step) makes an attempt to pick the correct space group automatically: it chooses that space group which has the highest symmetry (thus yielding the lowest number of unique reflections) and still a tolerable R<sub>meas</sub> compared to the R<sub>meas</sub> the data have in any space group (which is most likely a low-symmetry space group - often P1).
In many cases the automatic choice is the correct one, and re-running the CORRECT step is then not necessary. However, neither the correct enantiomorph nor screw axes (see below) are determined automatically by XDS.
In many cases the automatic choice is the correct one, and re-running the [[CORRECT.LP|CORRECT]] step is then not necessary. However, neither the correct enantiomorph nor screw axes (see below) are determined automatically by XDS.
=== Space groups to consider based on CORRECT suggestion ===
=== Space groups to consider based on CORRECT suggestion ===
