Dear colleagues,
I am in the process of refining a P2(1) structure that is marked by Scala as
twinned (L-test etc.) with a twinning fraction of ca. 0.2. I am still working
on the twinning problem, so no more details about this. But what puzzles me
right now is that, if I feed the data with a
Dear Uli,
It seems that you are dealing with psued-twinning when cell do not overlap
after rotation with twin operator. In these case what is in one resolution on
one of the orientation becomes another resolution in another orientation of
crystals
In short:. You have an operator R that
Dear Garib,
thanks for the clarification. I'll go back to the raw data and check for split
spots at high resolution (and give Mosflm a try; initially, the data were
integrated with XDS).
Cheers,
Uli
---
dr ulrich
Is this twinning or several crystals indexed according to different
conventions? You usually see evidence of twinning for each crystal if it is
really there..
Trigonal data can be indexed as h,k,l k,h,-k -h,-k,l or -k,-h,-l of course
so you have a 75% chance of getting the 2nd crystal on a
Hi all,
I will like to know, as a follow up of what Prof. Randy Read said, what
should be done to do the refinement against the measured data and not the
detwinned F( which refmac outputs in the mtz after twin refinement), during
subsequent refinements. And also, I would like to know how to
Garib may have more to say, but the first point would be to always include the
original data file as your input MTZ file for any cycle of refinement, whether
you're using Refmac in CCP4 or phenix.refine. (In phenix.refine, if you assign
the R-free data the first time you do refinement, it will
1) You should use measured data (after scala/aimless/truncate). In general
there may not be one to one relationship between observed data and asymmetric
unit (e.g. non-merohedral twinning) and it would not be possible to bring input
data to output file. Use original data
2) Internally refmac
On 2 Mar 2012, at 08:01, arka chakraborty wrote:
Hi all,
I will like to know, as a follow up of what Prof. Randy Read said, what should
be done to do the refinement against the measured data and not the detwinned F(
which refmac outputs in the mtz after twin refinement), during subsequent
Hi all,
Thanks for the express replies. Your insights along with the article by
Prof. Garib pointed to by Prof. Pavel completes the story for me.
Regards,
ARKO
On Fri, Mar 2, 2012 at 3:09 PM, Steiner, Roberto
roberto.stei...@kcl.ac.ukwrote:
On 2 Mar 2012, at 08:01, arka chakraborty wrote:
Dear CCp4ers,
A good morning to everyone.
Today, I have a structure that I initially refined in space group P6522,
1mol/asu.
Scaling stats (scalepack): 2.30-2.26A: Rsym=99.9%; I/sigma 3
2.61-2.55A: Rsym=39.6%, I/sigma 10
50.00-6.13: Rsym=6.4%
Some mild anisotropy in the resolution limits is
Hi Wolfram,
a few points:
- R-factors in twin refinement vs non-twin refinement are not directly
comparable:
G.N. Murshudov, Appl. Comput. Math., V.10, N.2, 2011, pp.250-261
http://www.science.az/acm/V10,%20N2,%202011,%20pdf/250-261.pdf
- did you make sure free-R flags assigned having
I'm worried when you say that you use the initial job's output MTZ. Refmac
replaces F with a detwinned F in the output file so you wouldn't be refining
against your measured data in the subsequent round.
Best wishes
Randy Read
Randy J. Read
On 2 Mar 2012, at 02:00, wtempel
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