Journal of Applied Crystallography

Volume 37, Part 4 (August 2004)

computer programs

J. Appl. Cryst. (2004). 37, 658-664 [ doi:10.1107/S0021889804011173 ]

PolySNAP: a computer program for analysing high-throughput powder diffraction data

G. Barr, W. Dong and C. J. Gilmore

Abstract: In high-throughput crystallography experiments, it is possible to measure over 1000 powder diffraction patterns on a series of related compounds, often polymorphs or salts, in less than one week. The analysis of these patterns poses a difficult statistical problem. A computer program is presented that can analyse such data, automatically sort the patterns into related clusters or classes, characterize each cluster and identify any unusual samples containing, for example, unknown or unexpected polymorphs. Mixtures may be analysed quantitatively if a database of pure phases is available. A key component of the method is a set of visualization tools based on dendrograms and pie charts, as well as principal-component analysis and metric multidimensional scaling as a source of three-dimensional score plots. The procedures have been incorporated into the computer program PolySNAP, which is available commercially from Bruker-AXS.

Keywords: powder diffraction; pattern matching; high-throughput crystallography; quantitative analysis; computer software.