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ShowPossibleCells v1

Summary

Show conventional cells corresponding to the UB stored with the sample for this peaks works space.

See Also

FindUBUsingFFT, FindUBUsingIndexedPeaks, FindUBUsingLatticeParameters

Properties

Name	Direction	Type	Default	Description
PeaksWorkspace	InOut	IPeaksWorkspace	Mandatory	Input Peaks Workspace
MaxScalarError	Input	number	0.2	Max Scalar Error (0.2)
BestOnly	Input	boolean	True	Show at most one for each Bravais Lattice
NumberOfCells	Output	number		Gets set with the number of possible cells.
AllowPermutations	Input	boolean	True	Allow permutations of conventional cells
Cells	Output	str list		A list of the different cells

Description

Given a PeaksWorkspace with a UB matrix corresponding to a Niggli reduced cell, this algorithm will display a list of possible conventional cells. The max scalar error property sets a limit on the maximum allowed error in the cell scalars, to restrict the list to possible cells that are a good match for the current reduced cell. The list can also be forced to contain only the best fitting conventional cell for each Bravais lattice type, by setting the best only property to true.

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:

import json
ws = LoadIsawPeaks("TOPAZ_3007.peaks")
FindUBUsingFFT(ws,MinD=8.0,MaxD=13.0)
number_of_cells, cells = ShowPossibleCells(PeaksWorkspace=ws)
print(f"Num Cells: {number_of_cells}")
cell1 = json.loads(cells[0])
cell2 = json.loads(cells[1])
print(f"First cell: Error={cell1['Error']:.3f} FormNumber={cell1['FormNumber']}, CellType={cell1['CellType']}, Centering={cell1['Centering']}")
print(f"Second cell: Error={cell2['Error']:.3f} FormNumber={cell2['FormNumber']}, CellType={cell2['CellType']}, Centering={cell2['Centering']}")

# the output can then be used by SelectCellOfType
SelectCellOfType(ws, CellType=cell1['CellType'], Centering=cell1['Centering'], Apply=True)
# or SelectCellWithForm
SelectCellWithForm(ws, FormNumber=cell1['FormNumber'], Apply=True)
# or SetUB
SetUB(ws, UB=cell1["UB"])

Output:

Num Cells: 2
First cell: Error=0.022 FormNumber=25, CellType=Monoclinic, Centering=C
Second cell: Error=0.000 FormNumber=44, CellType=Triclinic, Centering=P

Categories: AlgorithmIndex | Crystal\Cell

Source

C++ header: ShowPossibleCells.h

C++ source: ShowPossibleCells.cpp