Hmm - what is your space group, cell, and twin law? The mtz file output from REFMAC contains detwinned data - ie the column labelled as F is NOT the measured amplitude derived from the measured twinned intensities.
So in some SGs it is conceivable that an index has been generated.. This shouldnt happen with merohedral twinning but it can with pseudo-merohedral twinning. No the other hand, are you sure the extended resolution does not just involve the Free R column? look at the viewhkl summary to see if all columns extend to 2.0 resolution Eleanor On 21 October 2016 at 09:24, Robert Gustafsson <[email protected]> wrote: > Hi all, > > I am currently refining a structure that is at a resolution of 2.1Å and > slightly twinned. Below is the message in the aimless results: > > WARNING: the L-test suggests that the data may be twinned, so the > indicated Laue symmetry may be too high > Rough estimated twin fraction alpha from cumulative N(|L|) plot 0.209 > +/-(0.015) > Rough estimated twin fraction alpha from < |L| > 0.202 > Rough estimated twin fraction alpha from < L^2 > 0.192 > > I have been refining with twin refinement, and without, and using twin > refinement gives better R-factors, as expected. > > When looking in the results files more carefully however, it seems that > 0.1Å of data have been added to my data in the detwinning process! It > suddenly comes out of refmac with a 2.0 Å in both pdb and mtz resolution, > and it just suddenly seems to decide that for itself. I have looked for > differences in my input and there is none other than choosing amplitude or > intensity based twin refinement, instead of no twin refinement. Input mtz > and pdb are the same, but in the log file of refmac it suddenly uses 2.0 Å. > > This error is not captured afterwards, both Molprobity and PDBe validation > tool finds the structure to now be 2.0Å resolution, however i can see in > both refmac output and PDBe validation output that the completeness is > lowered (which I guess would be expected since some data does not exist…) > > So the question is, is this a bug of some sort, or should I have chosen > something in the input of refmac? I am using the latest update of ccp4 > (7.0.021) using the CCP4i interface. I have looked back at my files ( the > project started 2 years ago) and the problem was there as well, so it is > not a new problem. > > Sincerely, > Robert Gustafsson > > > _______________ > Robert Gustafsson > PhD Student > Department of Biochemistry and Biophysics > Stockholm University > 106 91 Stockholm, Sweden > > e-mail: [email protected] > > > >
