Student Project 3

Title

Crystal structure determination from unindexed powder diffraction patterns: heavy atom location

Description

When a compound does not form crystals suitable for single-crystal X-ray diffraction, it may be possible to determine its structure from powder diffraction data. Unfortunately, current methods fail in over 50% of all cases. In this project new pattern recognition techniques are applied, in combination with global optimization methods, to enhance the power of methods for structure determination from powder data, hopefully widening their application area.
In collaboration with the department of Analytical Chemistry, we have recently started to improve the first step in structure analysis from powder data, the determination of cell parameters (powder indexing). Integration with the structure determination step, the goal of this project, offers much of room for further improvements.

Keywords

Powder diffraction, structure analysis, X-ray diffraction, optimization, pattern matching, programming

Research program

Chemical Crystallography/ Analytical Chemistry: Method development

Contact person

When you are interested in this student project please contact:

[Icon: mailto Rene]  R. de Gelder    Phone 52842    Room N4018

References

  1. Direct Determination of Molecular Constants from Rovibronic Spectra with Genetic Algorithms.
     J.A. Hageman, R. Wehrens, R. de Gelder, W.L. Meerts, L.M.C. Buydens.
    Journal of Chemical Physics (2000), 113, 7955-7962.

  2. Fitting fluorescence spectra with genetic algorithms.
    J.A. Hageman, R. Wehrens, R. de Gelder, W.L. Meerts, L.M.C. Buydens.
    In Parallel Problem Solving from Nature VI, page 702. Springer Verlag, 2000. Lecture Notes in Computer Science.

  3. A Generalized Expression for the Similarity of Spectra: Application to Powder Diffraction Pattern Classification.
     R. de Gelder, R. Wehrens and J.A. Hageman.
    Journal of Computational Chemistry (2001), 22, 3, 273-289.

  4. Powder Pattern Indexing using the Weighted Crosscorrelation and Genetic Algorithms.
    J.A. Hageman, R. Wehrens, R. de Gelder, L.M.C. Buydens.
    Journal of Computational Chemistry (2003), 9, 1043-1051.

  5. Powder Pattern Indexing with Tabu Search.
    J.A. Hageman, R. Wehrens, R. de Gelder, L.M.C. Buydens.
    Submitted to Journal of Applied Crystallography.