Example why Platon/Addsym should be mandatory for crystallographers?

[Lachlan Cranswick]

I hope this isn't considered too "hyped up" but there is 
a new Platon/Addsym tutorial on the CCP14 site titled:

"An example of why Platon/Addsym should be considered a mandatory
program for all crystallographers"

  http://www.ccp14.ac.uk/tutorial/platon/addsymb.htm

This is based on the structure and spacegroups involved with the 
recent Short Communication in Acta Cryst "P1 or P-1? Corrigendum", 
Acta Cryst B56  (2000) 744 from Richard E. Marsh

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As posted before: "Addsym (building on Yvon LePage's powerful 
published MISSYM (C) algorithm) allows the identification of missed 
symmetry; which thus minimizes the chances of publishing structures 
in the wrong spacegroup.  It can also identify miss-fitting atoms for 
the benefit of the crystallographer who can then check if these 
are legitimately breaking a possible better symmetry."

The above tutorial includes all the NIXQAM related files in 
Shelx format that people can try out for themselves if in 
the mood.  

 The Original Triclinic P1 structure (published 1997)

 The revised Monoclinic C2 structure (1999)

 The Platon/Addsym Orthorhombic Fdd2 solution (2000)

It also shows how easy Platon can be used to routinely check 
for missing symmetry in structure files - and output an
updated Shelx file if some extra symmetry is found.

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Platon by Ton Spek is available off the internet for UNIX 
and Windows:

Homepage:
   http://www.cryst.chem.uu.nl/platon/
Mirrors:
UK http://www.ccp14.ac.uk/ccp/web-mirrors/platon-spek/platon/
CA http://ccp14.sims.nrc.ca/ccp/web-mirrors/platon-spek/platon/index.html
AU ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/web-mirrors/platon-spek/platon/index.html

FTP Download of Platon for UNIX:
   ftp://xraysoft.chem.uu.nl/pub/
Mirrors:
UK http://www.ccp14.ac.uk/ccp/ccp14/ftp-mirror/platon-spek/pub/
    ftp://ftp.ccp14.dl.ac.uk/ccp14/ftp-mirror/platon-spek/pub/
CA http://ccp14.sims.nrc.ca/ccp/ccp14/ftp-mirror/platon-spek/pub/
AU ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/ccp14/ftp-mirror/platon-spek/pub/

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Platon for Windows (ported by Louis Farrugia)
  http://www.chem.gla.ac.uk/~louis/platon97/
Mirrors:
UK http://www.ccp14.ac.uk/ccp/web-mirrors/farrugia/~louis/platon97/
CA http://ccp14.sims.nrc.ca/ccp/web-mirrors/farrugia/~louis/platon97/index.html
AU ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/web-mirrors/farrugia/~louis/platon97/index.html

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Any corrections, suggestions, etc for the above tutorial greatfully 
accepted. 

Lachlan.

-------
Lachlan M. D. Cranswick

Collaborative Computational Project No 14 (CCP14)
    for Single Crystal and Powder Diffraction
Daresbury Laboratory, Warrington, WA4 4AD U.K
Tel: +44-1925-603703  Fax: +44-1925-603124
E-mail: l.cranswick at dl.ac.uk  Ext: 3703  Room C14
                           http://www.ccp14.ac.uk