[ccp4bb]: refmac fom

["Bernhard Rupp" <br@llnl.gov>]

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Dear All :

Some rtfrm (r for refmac) yields
FWT and PHWT are amplitude and phase for weighted "2Fo-Fc" map (2mFo-DFcalc)

Sofar so good. Nice map. Not as nice as Shake&wARP, but it takes about
a factor of 10**2 less time ;-).

more rtfrm:
FOM = <m> - The "figure of merit" for this reflection.
How do/can I use this particular FOM in a map?
FP*FOM PHIC is quite a biased map. Where did m's buddy D go?
Rtfp (paper) ?

Also (Brent as well raised the question), qtfm (q for quoting):

"Rebuilding into these 2mFo-DFcalc and mFo-DFcalc maps
seems to be easier than using classic nFO-(n-1)FC and difference maps,
consistent with the established technique for SigmaA style maps.
One advantage here is that since the m and D values are based on the Free
set
of reflections they are less biased than the values obtained by the CCP4
version of SIGMAA after refinement"

Ok I can see that for the first (no previous rebuild) map - but then
in further cycles, haven't you actually taken info from your
crossvalidation set and (real space) refined against it?

Best, BR

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Bernhard Rupp
Macromolecular Crystallography and Structural Genomics
LLNL-BBRP L448                               Phone (925) 423-3273
University of California                     Phax  (925) 424-3130
Livermore, CA 94551                          email    br@llnl.gov
URL                                 http://www-structure.llnl.gov
TB Structural Genomics Consortium  http://www.doe-mbi.ucla.edu/TB
EU Mirror         http://www.ccp14.ac.uk/ccp/web-mirrors/llnlrupp
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