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Tutorials and Examples

LMGP suite for Windows by Jean Laugier and Bernard Bochu

(Laboratoire des Materiaux et du Génie Physique de l'Ecole Supérieure de Physique de Grenoble http://www.inpg.fr/LMGP/)

Basic Demonstration of Truecell on Y2O3 Crysfire results

The CCP14 Homepage is at http://www.ccp14.ac.uk

[Tutorials page] | [LMGP Suite Chekcell Index] | [LMGP Suite LePage Index] | [CRYSFIRE Tutorial Index] | [Powder Diffraction Indexing Resources]

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. Truecell can read *.SUM Summary results files generated by the Crysfire Powder Indexing Suite by Robin Shirley

CHEKCELL: Graphical Powder Indexing helper and Spacegroup Assignment Software has a version of Truecell included with it (accessible via the "Cell Parameters" window). Refer to the Chekcell tutorials for information involving Chekcell.

January 2001: Be aware that the new LePage for Windows could be far more effecient than Truecell. It would not hurt trying both programs for looking into possible sub-cell/super-cell effects.


Truecell (and Chekcell) can be obtained off the web at the the LMGP (Laboratoire des Materiaux et du Génie Physique de l'Ecole Supérieure de Physique de Grenoble http://www.inpg.fr/LMGP/) program suite site at:


The example data file is of a cubic Y2O3 sample using Indexing results from the Crysfire Powder Indexing Suite by Robin Shirley.

Crysfire can be run concurrently with Truecell and Chekcell but this assumes you already have some trial cells from Crysfire in the Crysfire *.SUM summary file. To see tutorials and obtain Chekcell, refer to the LMGP Suite Main Page.

In this demonstration, we will look at the best FOM result and find out what higher symmetry cells Truecell can generate, then match to other solutions.


Click on the Truecell icon or run the program via the windows explorer/windows file manager to bring up the Truecell starting interface.


Select the Crysfire icon to be prompted to open up a Crysfire *.SUM file and select the file of interest.


Click on the desired cell that you wish to perform a Truecell analysis on; tweak any parameters though the defaults are decently robust; then press the Run icon to start Truecell looking for alternative cells. A "% complete" bar will give an indication on how long this will take.


Truecell will then present any resulting cells it has found, the transformation matrix and whether it matches up with any other found solutions.

In this case Truecell has found a cubic cell which matches up with solution 5; the lowest solution on this list (which also happens to be the true cell for this form Y2O3). Performing a "Best Solution" analysis in the Chekcell software (which is part of the LMGP Suite) would flag this Cubic cell with a spacegroup of IA3 as the best suggested solution. As Truecell is also incorporated inside Chekcell, all of this could have course been conveniently performed inside chekcell.

Initial cell
Syst.   a      b      c    alpha  beta   gamma     Vo
ORTH  5.301  7.497  3.748  90.00  90.00  90.00    148.95

Found cell(s)
Syst.   A      B      C    Alpha  Beta   Gamma    Vo    V/Vo
CUBI 10.602 10.602 10.602  90.01  90.00  90.00  1191.6  8.00

                  Transformation Matrix            Crysf. sol
  ( 2.00 0.00 0.00),( 0.00 1.00 2.00),( 0.00-1.00 2.00)   5

Of course this is quite a contrived example as the "real" answer is known. In the case of an unknown, it is up to the user to choose the "best" and hopefully "true" cell. Truecell (and Chekcell) can give some extra and possibly vital food for thought.


[Tutorials page] | [LMGP Suite Chekcell Index] | [LMGP Suite LePage Index] | [CRYSFIRE Tutorial Index] | [Powder Diffraction Indexing Resources]

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