[ccp4bb] Second moments of Z but not twinning

Protein crystallography Programs for crystallography X-ray detectors
Basic tutorials:
Protein Peptide

CCP4bb navigation

CCP4bb <-- 2007 <-- June 2007 <-- 01 June 2007

Previous message:
Subject: Douglas Instruments Oryx crystallisation robots
From: Jan Dohnalek dohnalek {- at -} IMC {- dot -} CAS {- dot -} CZ
Date: 2007-06-01

Next message:
Subject: New version of clipper (includes buccaneer, pirate, ...) available from CCP4 download pages
From: "Remacle, F (Francois)" f {- dot -} remacle {- at -} DL {- dot -} AC {- dot -} UK
Date: 2007-06-01

Subject: Second moments of Z but not twinning
From: "Winter, G (Graeme)" g {- dot -} winter {- at -} DL {- dot -} AC {- dot -} UK
Date: 2007-06-01

Hi Folks,

I was wondering if there is a document somewhere explaining some of the
more interesting things which can be interpreted from the plot of second
moment of Z = I'/ anywhere? I've looked around and I can't find much
beyond the things pertaining to twinning, where it will have the magical
values of 2.0 or 1.5. What about if it is say 2.0 around the low
resolution regions but gets much bigger?

Looking at the truncate source code there is a note to the effect that
the second moments may be greater than two in when you have
pseudotranslational symmetry. In this case, however, I would expect that
the effect would be uniform across the resolution ranges... any
thoughts?

Any pointers would be greatly appreciated.

Thanks,

Graeme

CCP4bb navigation

CCP4bb <-- 2007 <-- June 2007 <-- 01 June 2007

Previous message:
Subject: Douglas Instruments Oryx crystallisation robots
From: Jan Dohnalek dohnalek {- at -} IMC {- dot -} CAS {- dot -} CZ
Date: 2007-06-01