This information is for those of you who still have need to determine cell
parameters from powder data outside of doing full Rietveld refinement, to
announce that a new version of UnitCell is available running under Windows
95 and 3.x. Thus UnitCell is now available for Windows, Mac and DOS.
Unlike most existing cell refinement programs, UnitCell does not require
initial estimates for cell constants; it uses a non-linear least squares
method, which allows the refinement to be carried out on the actual
observed data (e.g. two- theta in the case of angle-dispersive
monochromatic diffraction, energy in the case of energy-dispersive
diffraction). Furthermore, the program incorporates regression diagnostics,
particularly deletion diagnostics, to aid in the detection of outliers and
influential data which could be deleterious to the regressed results. These
diagnostic tools are particularly valuable in assessing the sensitivity of
the calculated results to the observations of individual Bragg peaks.
The program is available free from:
http://www.esc.cam.ac.uk/astaff/holland/UnitCell.html
Yours,
Simon Redfern.
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Dr Simon Redfern Tel: +44 1223 333475
Dept Earth Sciences Fax: +44 1223 333450
University of Cambridge
Downing Street
Cambridge, CB2 3EQ, UK www.esc.cam.ac.uk/astaff/redfern
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