Dear J.Kryst -
I am basically very puzzled to see that a 3.1 A structure has R and
Rfree of 15.3 and 23.8 % respectively !
Is that the diffraction limit of the crystal or is it a home dataset
collected with rather short exposures?
Is the Wilson B very low by any chance ?
As for the gab, I am too puzzled by the absolute values to even think
of it. I would had never expected a 3.1 A twin dataset
to give Rfrees anywhere else than the high 20's- let alone R below 20 !
Tassos
PS How do you pronounce J.Kryst really?
On 23 Oct 2007, at 6:54, john kryst wrote:
Hi ccp4bb !!
I am refining a 3.1 A resolution structure which has partial
twinning with twinning fraction 0.27 (space group P61).
When i refined in CNS with twin_lsq target i got 0.1529 and 0.2384
as R and Rfree.
There is almost 8-9% gap in R and Rfree. Map quality is good enough
to trace all
the atoms and ligands.
There is nothing much to build in the map too. Any suggestions to
reduce the gap in R and Rfree. I couldn't use shelxl because of the
resolution. Is it OK to stop refinement and submit the structure.
with warm regards
John
