Hmm - not sure if this would work but it is worth a try. Refine your model against twinned data to get PhiCalc
Go to Reflection Data Tools Calculate unusual map coeffs Give reflection file with I+ and I- from data processing ( They are twinned Is but maybe this will work) Phases from your best model Select "create anom map" And see what you get.. Maybe there is enough signal in the anomalous pairs to give peaks with good phases.. And please tell me if it works! I have no suitable data to test this idea.. Eleanor Give On Thu, 31 Mar 2022 at 20:10, Kay Diederichs <kay.diederi...@uni-konstanz.de> wrote: > Dear Petr, > > a map needs amplitudes and phases. In the case of the usual maps > (2Fobs-Fcalc and Fobs-Fcalc) calculated for twinned data, one can either > detwin the amplitudes, or take twinning into account in the Fcalc term. > > When calculating the anomalous map, I believe that detwinning of anomalous > differences would add a lot of noise. > Nevertheless you could try the detwin program; in the best case you get a > noisy anom map but with the ghost peaks > suppressed ... not sure if this can be done in ccp4i2 . > > Taking twinning into account in the Fcalc term is not necessary since the > Fcalc are not used in an anomalous map. > So I guess the best way is just calculating the map as if the data were > not twinned. You may get additional peaks > at a height of 0.29/0.71 the height of the correct peaks (and this > probably depends on whether the crystal symmetry has a > rotation axis parallel to the twin axis). > > Probably I should have read Z. Dauter's "Twinned crystals and anomalous > phasing" in Acta Cryst. (2003). D59, 2004-2016 > before writing this ... > > Good luck, > Kay > > On Tue, 29 Mar 2022 06:56:47 +0000, Petr Kolenko < > petr.kole...@fjfi.cvut.cz> wrote: > > >Dear colleagues, > >We have data from a twinned crystal (merohedral twinning with fraction of > 0.71) for which we want to see the anomalous map. Could you please guide me > how to calculate it using the i2? Running refinement with REFMAC5 with > merohedral twinning does not allow simultaneous generation of anomalous > maps. > >Best regards, > >Petr > > > >######################################################################## > > > >To unsubscribe from the CCP4BB list, click the following link: > >https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > > >This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > available at https://www.jiscmail.ac.uk/policyandsecurity/ > > > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > available at https://www.jiscmail.ac.uk/policyandsecurity/ > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
