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Information about GSAS

GSAS (General Structure Analysis System) is a comprehensive system for the refinement of structural models to both x-ray and neutron diffraction data. The GSAS package can be used with both single-crystal and powder diffraction data (Rietveld analysis), even both simultaneously. Neutron data can be either from single-wavelength instruments, or for those a bit more masochistic, time-of-flight instrumentation. Up to 99 different sets of data can be modeled using mixtures of up to 9 different phases.

GSAS has been created by Allen C. Larson and Robert B. Von Dreele of Los Alamos National Laboratory. Executable versions of GSAS are distributed more-or-less freely (see the friendly message from the Regents of the University of California, below), but the source code is not distributed (don't complain to me on this one, I agree with you).

Where do I get GSAS?

Where can I get an up-to-date GSAS manual?