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?

I recommend installing GSAS & EXPGUI together. See this downloads page for instructions and links.

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

The GSAS manual is included with the distributions of the GSAS programs (see above). It is a ~230 page PDF file (1.7Mb) that contains three sections: tutorials, mathematical basis & file structures. Every GSAS user should take the time to read the "mathematical basis" section (pages 125-179 in 1/19/01 version)!

The manual can be found on the

What computers does GSAS run on?

GSAS runs on all modern operating systems and older versions may possibly be located for Silicon Graphics and openVMS computers.

GUI tools for GSAS

EXPGUI is a a package that allows many of the most commmonly used features within GSAS to be accessed (but far from all of them). See the EXPGUI website.

Citations

The folks that have written GSAS get very little credit for their massive efforts. By including a reference to GSAS in your papers, you can help see that the citation index will reflect the importance of their contribution.
• A.C. Larson and R.B. Von Dreele, "General Structure Analysis System (GSAS)", Los Alamos National Laboratory Report LAUR 86-748 (2000). [link to PDF copy of manual]
Much of the same is true for EXPGUI.
• B. H. Toby, EXPGUI, a graphical user interface for GSAS, J. Appl. Cryst. 34, 210-213 (2001). [link to PDF version of paper]

Bugs in GSAS or EXPGUI

Please convince yourself that the problem is not yours. (User errors are far more frequent than software bugs, IMHO.)
• Report GSAS problems to Bob Von Dreele (vondreele@anl.gov).
• Report EXPGUI problems to Brian Toby (brian.toby@ANL.gov)

---

GSAS is written by: Allen C. Larson and Robert B. Von Dreele MS-H805, Los Alamos National Laboratory, Los Alamos, NM 87545. Problems, questions or kudos concerning GSAS should be sent to Robert B. Von Dreele at vondreele@anl.gov

GSAS is Copyright, 1984-2001, The Regents of the University of California. The GSAS software was produced under a U.S. Government contract (W-7405-ENG-36) by the Los Alamos National Laboratory, which is operated by the University of California for the U.S. Department of Energy. The U.S. Government is licensed to use, reproduce, and distribute this software. Permission is granted to the public to copy and use this software without charge, provided that this notice and any statement of authorship are reproduced on all copies. Neither the Government nor the University makes any warranty, express or implied, or assumes any liability or responsibility for the use of this software.

Neither the author nor the U.S. Government makes any warranty, expressed or implied, or assumes any liability or responsibility for the use of this information or the software described here. Brand names cited here are used for identification purposes and do not consitute an endorsement by NIST.

Last modified 28-July-2021 by website owner: NCNR (attn: Craig Brown) $Revision: 1.13 $ $Date: 2007/01/25 22:44:45 $