SelectCellWithForm v1

../_images/SelectCellWithForm-v1_dlg.png

SelectCellWithForm dialog.

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 PeaksWorkspace 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

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 corresponding to the selected cell AND the peaks will be re-indexed using the new UB matrix. 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: “Lattice Symmetry and Identification – The Fundamental Role of Reduced Cells in Materials Characterization”, Alan D. Mighell, Vol. 106, Number 6, Nov-Dec 2001, Journal of Research of the National Institute of Standards and Technology, 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 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 lattice.a(),lattice.b(),lattice.c(),lattice.alpha(),lattice.beta(),lattice.gamma()

Output:

Lattice before SelectCellWithForm:
8.60581864273 11.935925461 11.9418127661 107.429088323 98.7529124665 98.9511934747

Lattice after SelectCellWithForm:
14.1310511523 19.247332564 8.60581864273 89.8811706749 105.07133377 89.970386662

Categories: Algorithms | Crystal\Cell