Re: [sdpd] For Powder Indexing: New Truecell software and Truecell enabled Chekcell update

[Georges Denes <gdenes...@vax2.concordia.ca>]

Hi:

I have the reverse problem:  one superstructure reflection forces me to
quadrupole the three parameters, i.e. a, b and c of an orthorhombic basic
cell, which multiplies the volume by 64.  However, I suspect there might be
a smaller unit-cell, with a different orientation of the unit-cell axes,
and possibly a different crystal system.  I am wondering how to check this
and find possible smaller cells that would index every peak.  In addition
to the superstructure reflection, there are many new peaks, weaker,
however, they are at higher angles where there are too many choices of
indexation in the 4a x 4bx 4c supercell.  Anybody has an idea how to tackle
this problem?
Every suggestion will be welcome.
Thank you.

Georges 

	*****************************************
	Georges Y.M. DENES
	Associate Professor of Chemistry
	CONCORDIA UNIVERSITY
	Department of Chemistry and Biochemistry
	1455 De Maisonneuve Blvd. W.
	Montreal, Qc, H3G 1M8
	CANADA
	Tel.:   (514) 848-3346 (office)
		 (514) 848-3366 (secretary)
	Fax: 	 (514) 848-2868
	e-mail:  gdenes...@vax2.concordia.ca
	*****************************************


=====================================================================

At 06:10 AM 5/26/00 +0100, you wrote:
>
>There is are new addition to the LMGP suite by Jean Laugier and 
>Bernard Bochu called "Truecell".
>
>Truecell searches for more symmetric, higher symmetry cells that could
>be a "better" solution to powder indexing data. This can be useful where
>powder indexing programs favour small, low symmetry cells; and a
>higher volume, higher symmetry cell could be a better solution.
>
>The Chekcell graphical powder indexing helper and spacegroup
>assignment software now has a version of Truecell included with it - 
>accessible via the "Cell Parameters" window. 
>
>(Truecell (and Chekcell) can read *.SUM Summary results files generated 
>by the Crysfire Powder Indexing Suite by Robin Shirley)
>
>Tutorial runthroughs showing Truecell in action are available
>from the CCP14 website:
>
>  Basic Demonstration of Truecell on Y2O3 Crysfire results
>    http://www.ccp14.ac.uk/tutorial/lmgp/trucella.htm
>
>  Using Truecell on a high FOM monoclinic trial solution
>    http://www.ccp14.ac.uk/tutorial/lmgp/truecell_large_hex.htm
>
>----
>
>Truecell and Chekcell 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/
>  AU:
ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/web-mirrors/lmgp-laug
ier-bochu/
>
>
>Crysfire Powder Indexing Suite Download:
>  UK: http://www.ccp14.ac.uk/ccp/web-mirrors/crys-r-shirley/
>  CA: http://ccp14.sims.nrc.ca/ccp/web-mirrors/crys-r-shirley/
>  AU:
ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/web-mirrors/crys-r-sh
irley/
>
>Cheers,
>
>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...@dl.ac.uk  Ext: 3703  Room C14
>                           http://www.ccp14.ac.uk
>