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# SelectCellWithForm v1¶

## Summary¶

Select a conventional cell with a specific form number, corresponding to the UB stored with the sample for this peaks works space.

## Properties¶

Name

Direction

Type

Default

Description

PeaksWorkspace

InOut

IPeaksWorkspace

Mandatory

Input Peaks Workspace

FormNumber

Input

number

Mandatory

Form number for the desired cell

Apply

Input

boolean

False

Update UB and re-index the peaks

Tolerance

Input

number

0.12

Indexing Tolerance

NumIndexed

Output

number

The number of indexed peaks if apply==true.

AverageError

Output

number

The average HKL indexing error if apply==true.

AllowPermutations

Input

boolean

True

Allow permutations of conventional cells

TransformationMatrix

Output

dbl list

The transformation matrix

## Description¶

Given a PeaksWorkspace with a UB matrix corresponding to a Niggli reduced cell, this algorithm will allow the user to select a conventional cell corresponding to a specific form number from the Mighell paper. If the apply flag is not set, the information about the selected cell will just be displayed. If the apply flag is set, the UB matrix associated with the sample in the PeaksWorkspace will be updated to a UB matrix corresponding to the selected cell AND the peaks will be re-indexed using the new UB matrix. The output transformation matrix $$M$$ will change $$UB$$ to $$UBM^{-1}$$ and map each $$(HKL)$$ vector to $$M(HKL)$$. It can be further used by the TransformHKL algorithm. NOTE: The possible conventional cells, together with the corresponding errors in the cell scalars can be seen by running the ShowPossibleCells algorithm, provided the stored UB matrix corresponds to a Niggli reduced cell.

This algorithm is based on the paper: Alan D. Mighell, Lattice Symmetry and Identification—The Fundamental Role of Reduced Cells in Materials Characterization. Journal of research of the National Institute of Standards and Technology 106.6 (2001): 983, available from: nvlpubs.

## Usage¶

Example:

ws=LoadIsawPeaks("TOPAZ_3007.peaks")
FindUBUsingFFT(ws,MinD=8.0,MaxD=13.0)
print("Lattice before SelectCellWithForm:")
lattice = ws.sample().getOrientedLattice()
print(" ".join("{:.9f}".format(x) for x in [lattice.a(), lattice.b(), lattice.c(),
lattice.alpha(), lattice.beta(), lattice.gamma()]))
SelectCellWithForm(PeaksWorkspace='ws', FormNumber=25, Apply=True)
print("\nLattice after SelectCellWithForm:")
lattice = ws.sample().getOrientedLattice()
print(" ".join("{:.9f}".format(x) for x in [lattice.a(), lattice.b(), lattice.c(),
lattice.alpha(), lattice.beta(), lattice.gamma()]))


Output:

Lattice before SelectCellWithForm:
8.605818643 11.935925461 11.941812766 107.429088323 98.752912466 98.951193475

Lattice after SelectCellWithForm:
14.131051152 19.247332564 8.605818643 89.881170675 105.071333770 89.970386662


Categories: AlgorithmIndex | Crystal\Cell