Hi Yamei, A possible explanation is that the actual space group is P4(2) but the data are perfectly hemihedrally twinned, which makes the crystal appear to possess 422 point group symmetry. No twin operators are found because merohedral twinning is not possible in crystals with true 422 symmetry. If you analyze the data after reprocessing in P4(2) a twin law will then be found.
Philip On Wed, Jul 2, 2014 at 11:04 PM, Yamei Yu <ymyux...@gmail.com> wrote: > HI all, > > I have a data set processed to P42 21 2 (the space group was suggested > by pointless ). then I use phenix.xtriage to analysis the data. I was > confused by the phenix.xtriage result. > According to the following number it is twin data, but why it couldn’t > find any possible twin law? > > Determining possible twin laws. > > 0 merohedral twin operators found > 0 pseudo-merohedral twin operators found > In total, 0 twin operator were found > > > Mean |L| :0.378 (untwinned: 0.500; perfect twin: 0.375) > Mean L^2 :0.205 (untwinned: 0.333; perfect twin: 0.200) > > > How could be that? Is it twin or no twin? > > Please find the log file of phenix.xtrage in attachment. > > Thank you so much for your suggestion! > > > ************************************************ > > Yamei Yu > >
