[ccp4bb]: automatic matrix weighting in refmac

["Jorge Iulek" <iulek@interponta.com.br>]

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Dear all,

    At using the arp script (under the ccp4i) for finding solvent molecules
in a structure, I notice today that the refmac5 module (within the script)
has an "auto" option for the weighting between x-ray and geometric terms.
This option is not available when I run refmac alone (under the ccp4i) and
is not documented either in the off-line or in the on-line manuals.
Nevertheless, I could run refmac5 out of the interface with this option
(auto), where the log file shows it recognizes the option with an "Automatic
weighting - an Attempt" message.
1) Why is this option (automatic weighting between x-ray and geometrical
terms) not commented in the manuals ? Why is there the "attempt" message in
the log file ? Is it still unstable or not recomended in refmac5 ? So, why
other refinement softwares use the automatic weighting ? Is it always
vantageous ?
2) What is the criteria used to decide what the best weight is (at least by
the automatic word) ? I myself have been using what was commented some
months ago in the bb, to look at the best R-free's after  trying several
weight values for refining.
    Thanks,
************************************************************************
Prof. Jorge Iulek, Ph. D.
Protein Purification and 3D Structure Determination Group
Department of Chemistry
Biotechnology Center
State University of Ponta Grossa - PR
Brazil

Office phone: ++ 55 (42) 220-3062
Home phone  : ++ 55 (42) 224-6182
Fax  : ++ 55 (42) 220-3342


e-mail: iulek@interponta.com.br
              iulek@uepg.br
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