Glass Reflections
Cambridge 7th to 9th September

Presenting Author:
Matt Tucker
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article posted 13 Mar 2015

Matt Tucker

Dr Matt Tucker has been an instrument scientist in the Crystallography Group at the ISIS Facility, Rutherford Appleton Laboratory since 2005. Since 2013, he has also had a joint appointment at the Diamond Light Source. At ISIS he is an instrument scientist on the high flux medium resolution POLARIS diffractometer, which is a world-class instrument for total scattering measurements. At Diamond he is helping to design, build and ultimately run Europe's first dedicated Xray-PDF beamline. Previously, he was a PDRA for 6 years in the Department of Earth Science at the University of Cambridge after obtaining his PhD from the University of Kent at Canterbury. Matt's research interests focus on using and developing total scattering techniques for the study of disordered crystalline materials and he is the co-author of over 100 refereed publications. Research highlights include studies of negative thermal expansion, pressure induced amorphisation and colossal thermal expansion. He has successfully led the development of a Reverse Monte Carlo program (RMCProfile) specifically for the analysis of total scattering data of polycrystalline materials (with Prof. David Keen, Prof. Martin Dove, Dr Igor Levin and several other contributors). This program suite is freely available for download at Matt is currently the Chairman of the Physical Crystallography Group (PCG) of the British Crystallography Association (BCA) and the Structural Condensed Matter Group (SCMP) of the Institute of Physics (IoP) (

XPDF and a step towards Complex Modelling
Matt Tucker
ISIS Facility & Diamond Light Source, Rutherford Appleton Laboratory,
Harwell Science and Innovation Campus, Didcot,
Oxfordshire OX11 0QX, U.K.

XPDF, a new beamline at the Diamond Light Source, will be Europe's first dedicated Pair Distribution Function (PDF) instrument. Using the x-ray PDF technique, also know as x-ray total scattering, to study crystalline materials has been growing in popularity over the past decade. However, the technique of course was originally perfected and used to study the atomic structure of amorphous materials. So this means the new XPDF beamline will be extremely useful for the study of glasses and I will give an update on the status of the project and an overview of it capabilities.

To gain the most useful information from total scattering data it is often necessary to produce atomistic model with computation methods. One such method is reverse Monte Carlo (RMC)[1], here a large box of atoms is constructed with the correct composition and density. Then atom chosen at random, are moved by a random amount until the calculated total scattering matches the experimental data. This comparison back to the data rather than to an empirical potential is what make this reverse rather than classical Monte Carlo. The resulting atomistic configuration can then be analysed to provide a more detailed understand of the environment around the various atom types.

As with the experimental technique we have been developing RMC methods for the study of crystalline materials over the past decade [2]. However, since they are built on the methods originally developed for amorphous materials, the new development can equally be applied to amorphous systems. I will give several examples of how the new methods have been used to study phenomena such as solid-state amorphisation and how they are moving us closer to a complex modeling regime [3].


1. R. McGreevy, L. Pusztai, Mol. Simul., 1988, 1, 359

2. RMCProfile: reverse Monte Carlo for polycrystalline materials M G Tucker, D A Keen, M T Dove, A L Goodwin, Q Hui J. Phys.-Condes. Matter 19 335218 (2007) - also more information and the program available at

3. S. Billinge, I. Levin, Science, 2007, 316, 561-565