Major bugfix version of Chekcell powder indexing helper tool

L. Cranswick lzc at dl.ac.uk
Mon Jun 3 00:21:56 EST 2002


Some rather serious bugs were introduced in recent versions
of Chekcell to get around problems on how TAUP reports 
monoclinic cells (this affected Hexagonal and Rhombohedral cells) 

There is also a new 2nd/3rd June 2002 version of Chekcell for Windows
graphical indexing helper tool for assigning cells and spacegroups
from powder data by Jean Laugier and Bernard Bochu - part of
the LMGP software suite.
(Chekcell interlinks with Robin Shirley's Crysfire powder indexing
suite)

Download:
 UK:  http://www.ccp14.ac.uk/ccp/web-mirrors/lmgp-laugier-bochu/
 CA:  http://ccp14.sims.nrc.ca/ccp/web-mirrors/lmgp-laugier-bochu/
 US:  http://ccp14.semo.edu/ccp/web-mirrors/lmgp-laugier-bochu/
 AU:  http://ccp14.minerals.csiro.au/ccp/web-mirrors/lmgp-laugier-bochu/

Chekcell Tutorials:
 UK:  http://www.ccp14.ac.uk/tutorial/lmgp/#chekcell
 CA:  http://ccp14.sims.nrc.ca/tutorial/lmgp/#chekcell
 US:  http://ccp14.semo.edu/ccp/tutorial/lmgp/#chekcell
 AU:  http://ccp14.minerals.csiro.au/tutorial/lmgp/#chekcell

It is recommended anyone using Chekcell to aid in powder
indexing download this update.

----------------

Also, if not obvious from the Chekcell interface, when you find
a cell you are happy with it - make sure to test this with Ton 
Spek's "LePage" software.  LePage for Windows is provided 
within Chekcell.

i.e.,
If you have found high FOM monoclinic, orthorhomic, hexagonal
cells, etc - LePage super-cell searching can commonly find higher 
symmetry cells that fit all the lines with less superfluous
reflections.  This is due to the habit of many indexing programs in
favouring low volume low symmetry cells over the "true" high volume, 
high symmetry cell.  LePage super-cell searching can provide an 
important tool for helping obtain (or confirm) a good high symmetry cell.

An example runthrough of this is at:
  
 Using Ton Spek's Lepage within Chekcell to find super-cells and 
 better powder indexing trial cell solutions 

  http://www.ccp14.ac.uk/tutorial/lmgp/chekcell_lepage.html

Lachlan.



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

1st June 2002 until 1st July 2002
 Geochemistry: Lamont-Doherty Earth Observatory of Columbia University
 PO Box 1000, 61 Route 9W Palisades, New York 10964-1000 USA
 Tel:  (845) 365-8302   Fax:  (845) 365-8155 

Collaborative Computational Project No 14 (CCP14)
    for Single Crystal and Powder Diffraction
  Birkbeck University of London and Daresbury Laboratory 
Postal Address: CCP14 - School of Crystallography,
                Birkbeck College,
                Malet Street, Bloomsbury,
                WC1E 7HX, London,  UK
Tel: (+44) 020 7631 6850   Fax: (+44) 020 7631 6803
E-mail: l.m.d.cranswick at dl.ac.uk   Room: B091
WWW: http://www.ccp14.ac.uk/





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