Bugfix version of Chekcell powder indexing helper tool

L. Cranswick l.m.d.cranswick at dl.ac.uk
Thu Jan 3 09:03:21 EST 2002


There is also a new 3rd January 2001 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)

  http://www.ccp14.ac.uk/tutorial/lmgp/
  http://ccp14.sims.nrc.ca/tutorial/lmgp/
  http://ccp14.semo.edu/ccp/tutorial/lmgp/

Chekcell Download:
  http://www.ccp14.ac.uk/ccp/web-mirrors/lmgp-laugier-bochu/
  http://ccp14.sims.nrc.ca/ccp/web-mirrors/lmgp-laugier-bochu/
  http://ccp14.semo.edu/ccp/web-mirrors/lmgp-laugier-bochu/
  
Crysfire powder indexing suite 
  (comes with Ito, Dicvol, Treor, Taup, Kohl, Fjzn, Lzon and Losh):
  http://www.ccp14.ac.uk/tutorial/crys/
  http://ccp14.sims.nrc.ca/tutorial/crys/
  http://ccp14.semo.edu/ccp/tutorial/crys/

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Speed of generating HKLs has been improved. Previously this would show 
up as a problem when handling large Cubic cells.

Bug when manually inputting the HKL to peak matching tolerance has 
been fixed 

Example files given with Chekcell have been rehashed:  where data allows, 
there is an "empir" directory for "empirical peak fitting" and "fundpar" 
directory for "fundamental parameters" peak fitting (i.e., using XFIT 
in Fundamental Parameters mode (Coelho and Cheary)). 

"Fundamental parameters" tends to result in higher FOM (Figures of Merit) 
for trial cells.  

e.g.,:

                              Top FOM "Empirical"   Top FOM "Fund Param"
No visible peak overlap 
ambiguity (cubic)              214.4                         289.3

Peak overlap (monoclinic)       45.5                          74.8

----------

Some peak overlap (Cubic)       23.6                          40.8
rescaled peak data (r=0.3)    (top sol NOT "true cell")
                                            (top solution is "true cell")

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XFIT Peak profiling with Coelho and Cheary "fundamental parameters" 
peak profiling (only applicable in XFIT to Bragg-Bretano Geometry):
  http://www.ccp14.ac.uk/tutorial/xfit-95/xfit.htm
  http://ccp14.sims.nrc.ca/tutorial/xfit-95/xfit.htm
  http://ccp14.semo.edu/ccp/tutorial/xfit-95/xfit.htm

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Doing a recap on late last year:

A new Chekcell feature is that of a "Density Explorer / Z Explorer"
that can be very useful for organics / pharmaceuticals / organometallics 
(and other phase systems)

Just put in your molecular formula - a "density range" or "Z range"
and click "Calc" to generate a Density/Z table to the right of all
your trial cells (irrespective you have only 1 or 5000 trial cells)

Brief runthrough of the "Density / Z Explorer" within Chekcell at:

  http://www.ccp14.ac.uk/tutorial/lmgp/chekcell_density_explorer.html
  http://ccp14.sims.nrc.ca/tutorial/lmgp/chekcell_density_explorer.html
  http://ccp14.semo.edu/tutorial/lmgp/chekcell_density_explorer.html

The Density explorer menu can also be called within the Truecell and
LePage interfaces after generating derivative cells (super cells - sub
cells)

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Lachlan.




-- 
-----------------------
Lachlan M. D. Cranswick
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 6849   Fax: (+44) 020 7631 6803
E-mail: l.m.d.cranswick at dl.ac.uk
WWW: http://www.ccp14.ac.uk/





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