DANSE Software serving the community Simon Billinge, Columbia University Brent Fultz, California Institute of Technology, DMR ) New Science Through better software [1] Qiu et al.J. Appl Crystallogr. (2003) [2] Farrow et al., J. Phys: Condens. Mat. (2007) The recent development of the rapid acquisition pair distribution function (RAPDF) data collection method [1] for the first time allows local and nanoscale structure to be studied in a time resolved way with ms to minutes time-resolution. Such measurements result in large numbers of data-sets which need further processing to extract the scientific information of interest: the nanoscale structure. The PDFgui application of the DANSE software project [2] allows quantitative refinements to be carried out rapidly on such data. This example shows a recent study of the spin- dimerization transition in the frustrated magnetic system CuIr 2 S 4. At 215K on cooling Ir-Ir dimers form in the local structure as Ir forms short bonds with its neighbor. It is possible to destroy the dimer long-range order in different ways but understanding the underlying physics relies on a study of the local dimers made possible by the PDFgui software. With the help of PDFgui, local Ir-Ir dimer formation could be followed carefully on cooling and warming extracting a hysteresis curve of the behavior from many datasets. The plot and inset shows how the measured RAPDF curve, showing the local structure, changes on dimer formation. The blue and red points on the right show the phase fraction of dimerized material extracted from PDFgui refinements.

DANSE team serving the community Simon Billinge, Columbia University Brent Fultz, California Institute of Technology, DMR PDFgui package public release Software downloads: Software Developers: P. Juhas, C. Farrow, J. Liu, W. Zhou The first full public release of the PDFgui data modeling program, developed as part of DANSE, took place this year. The program is distributed under an open source license and is free for scientists doing academic research. It is available for download on Windows, Linux and Mac OSX platforms. Since its release the program has been successfully downloaded >500 times. Community outreach activities include vibrant Google-group discussion forums for answering users’ questions about usability and for bug reporting and feature requests (Diffpy-uesrs and Diffpy-dev, respectively) as well as hands on software classes and presentations at meetings. The picture shows attendees at the hands-on software workshop at the American Conference on Neutron Scattering in Sante Fe NM. Forty percent of the attendees of this meeting were women or minorities. An upcoming international workshop will take place in Warsaw, Poland, and has 62 people registered. Instructors and students at the PDFgui hands-on workshop, May 11 th 2008, Santa Fe, NM. ~40% of attendees were women or minorities. Screenshot of the PDFgui downloads page showing the log of successful downloads