Hi Siva,
SFCHECK (part of CCP4i) has a very handy option for this. From the
command line:
% mkdir mydir
% sfcheck -f mydata.mtz -po mydir/ -out u -r
% gv mydir/sfcheck_XXXX.ps
(or ghostscript/xpsview/whatever postscript viewer you have)
This will generate a number of output files, including a useful
postscript summary of your data (including twinning operator and
fraction, if detected). If twinning is detected sfcheck will also
output a detwinned dataset (sfcheck.hkl) which is in CIF format -
although at least with my version before you convert the CIF to MTZ in
CCP4i, you have to change the line in the .hkl file that reads
"_refln.F_meas_au_sigma" to "_refln.F_meas_sigma_au".
However, unless your twinning fraction is low and your data behaves well
under detwinning, I would suggest using the twinned data as is, in
SHELX, CNS or PHENIX.
Best of luck,
James
siva charan wrote:
hello
I have a data set to 2.4 A, which has space group of *P21 *. From the
cumulative intensity distribution graph, indicates that data is
twinned . To run the detwin program in ccp4, one has to know the
twinning operator. Can anybody help me, how can I get the twinning
operator for monoclinic space group. I have checked for twin operators
at http://www.ccp4.ac.uk/dist/html/twinning.html, but there are no
twining operators for monoclinic space group.
regards
siva
