[ccp4bb]: CNS composite_omit_map

[Sebastiano Pasqualato <sebastiano.pasqualato@lebs.cnrs-gif.fr>]

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Dear all,
does anybody know exactly how CNS performs the calculation of its 
composite_omit_map? All I could find in the CNS site is that:
"small regions of the model are systematically excluded. A small map is 
made covering the omitted region. These small maps are accumulated and 
written out as a continuous map covering the whole molecule (or the defined 
region)."
... not too much, isn't it??
How are the omit maps merged? Why is it unuseful (as stated in the input 
file) to perform an Fo-Fc map, and a 2Fo-Fc map is recommended?
Thanks a lot,
Sebastiano




Sebastiano Pasqualato
CNRS,
Laboratoire d'Enzymologie et Biochimie Structurales
1, Avenue de la Terrasse
91198 Gif-sur-Yvette Cedex FRANCE

phone +33 (0)1.69.82.34.97
fax +33 (0)1.69.82.31.29