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## Truecell rules and logic

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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.

## Truecell rules and logic

```From: "Jean Laugier" [jean.laugier2@wanadoo.fr]
To: "Lachlan Cranswick" [l.m.d.cranswick@dl.ac.uk]
Subject: Re: Chekcell and Truecell
Date: Tue, 27 Nov 2001 15:11:21 +0100

1-If  the "All" option is selected, all the solutions with a minimum
monoclinic symetry is displayed. But in my opinion it is not a good thing,
because a lot of low symetry solutions exists when the starting cell is
cubic for example.

2-When the the "All" option is not selected, the program never searches the
triclinic cells and verifies the following rules:

-If the starting cell is cubic, only cubic multiple cells can be found.

-If it is tetragonal, only tetragonal, hexagonal and rhomboedral cells can
be found.

-If it is orthorhombic, Truecell searches all cell  kinds except monoclinic
and triclinic.

-If it is hexagonal, Truecell does not search orthorhombic, or monoclinic
and triclinic.

-If it is rhomboedral, Truecell does not search hexagonal cells, or
monoclinic and triclinic.

-If it is monoclinic, Truecell does not search triclinic cells.

If the user's queries don't correspond to these rules an error message is
displayed. It's a complicated, but I think it's logical.

Cheers,

Jean```

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