equilibrium of group II-VI semiconductors at high P and T, and D. Haüsermann on the latest results from the very active group at beamline ID30 at the ESRF, including work on semiconductor phase diagrams in a Paris-Edinburgh large-volume cell. M. McMahon complemented this session with an invited poster oral on new structures and transitions in GaAs.
The final day featured spirited sessions on ices and hydrogen bonding, and spectroscopic studies. W. Kuhs provided an overview of ices and ice clathrates at lower pressures, followed by talks dealing with phase transitions and structures of liquid water and amorphous (glassy) and crystalline ice (D. Klug and M.-C. Bellissent-Funel). J. Loveday presented results of the Paris-Edinburgh collaboration on neutron diffraction study of ices up to 25GPa, and R. Hemley on studies of ice to megabar pressures and D. Marx on complementary ab initio calculations of protons in ice in that range.
The final session of the meeting, "spectroscopic studies at high pressure", covered the latest developments in what is/will be possible in 1999. S. Klotz presented work much extending the pressure range of inelastic neutron scattering. M. Pasternak spoke of his Mössbauer spectroscopy on FeO and advanced pressure cells for studies beyond 100GPa. W. Bassett and R. Mayanovic gave closely-related talks dealing with the design of a special DAC to allow EXAFS studies at low-energy edges. They presented results on zinc (II) complexes in hydrothermal fluids. The meeting was given a splendid inale with a talk from H. Mao on recent developments in X-ray spectroscopy and the many exciting prospects of the new beamline concept at the APS (the High Pressure Collaborative Access Team or HP-CAT).
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Carol Brock and an old friend from Kentucky attending the AsCA meeting in Malaysia (Photo by WLD) |
Tours of the APS and IPNS facilities, were conducted in parallel
with posters one afternoon. The highlight of the banquet was
a presentation by Malcolm McMahon of essential linguistic guidelines
for those attending the Glasgow Congress. In bare knees and a
tartan car-rug, he assailed the crowd with some of the finest
Scots humor heard since Sean Connery played that Russian submarine
commander!
The participants plan to meet again in Glasgow where six oral
sessions will continue to develop many of the topics of this
landmark meeting.
John Parise and Richard Nelmes
Crystal Simulation Workshop
A workshop on Simulating Crystals as a Teaching Tool and Analyzing
Defect Structures will be held during the IUCR Meeting in Glasgow,
Aug. 11, 1998, under the auspices of the German Crystallographic
Assn.
Simulating crystals in a computer is an efficient tool to teach
crystallography and diffraction physics. Clusters of atoms and
crystal structures, free from constraints imposed by real materials
can be used to explain and explore different features of diffraction.
Students can modify structures and study the impact of modifications
on the diffraction pattern. The analysis of simulated crystal
illuminates geometric aspects of crystal structures.
Simulation of structures containing defects is a useful tool
for the interpretation of diffuse scattering. Simulations allow
fast and flexible realizations of complex defect models. The
corresponding Fourier transform is readily calculated and can
be compared to the observed data. New algorithms allow a quantitative
analysis of diffuse scattering.
Participants will learn how to use the DISCUS program and create
crystal structures and their corresponding Fourier- transforms
for many applications that have proven highly efficient in our
teaching experience.
The participants will be shown techniques related to crystal
defects, analysis of diffraction patterns with Monte Carlo, and
Reverse Monte Carlo methods. For more information, visit the
website at http://www.uni-wuerzburg.de/mineralogie/crystal/
workshop.html.
