Crystallographic Information Framework



The Gnu Xtal System is a modular suite of software oriented primarily towards small-molecule crystallography, but which also covers some powder diffraction and charge-density work.


If you wish to install and use this software you should download the most up-to-date version from the above Web site. The links below are to copies which are suitable for browsing or for use if the primary Web site is not available. However, they may be out of date and lack the full functionality of the latest version.


Version 3.7 is maintained as an open-source collaborative project. It is directly descended from the Xtal System (with only a minor name change) and thereby from the original XRAY76 suite. It was conceived, created and maintained for many years by Syd Hall (the originator of the Crystallographic Information File (CIF)) at the University of Western Australia. Numerous other developers have contributed to this suite over the years. Use of the RATMAC preprocessor (see Language and Platform below) encouraged a coding style in which almost every single line of code was documented, aiding both the development and maintenance of the code base. The modular design of the software and its use of archives for conveying calculation results between different program modules accessed by a nucleus of common IO routines has resulted in a very robust and stable program suite and facilitated the development of diverse calculation modules by many different authors.

Language and platform

The software is written in Fortran 77 generated from a RATionalized MACro (RATMAC) preprocessor to insulate the code base from variations in F77 dialects and operating-system specific functionalities. It maintains a dependency on Tcl/Tk, and (for the program SURFIN) on OpenGL libraries also. The Tcl/Tk dependence is customizable to a great extent.


Terms and conditions of use

Copyright in the software © 1983-2001 The Xtal System of Crystallographic Software. The University of Western Australia. All Rights Reserved
Copyright © The Gnu Xtal System of Crystallographic Software.
Xtal was developed by research workers supported by grants from a wide range of agencies. The names of the program authors are listed at the start of each program description and it is important that acknowledgement is given to the author(s) in any resulting publications and presentations.

Please use the following acknowledgement formats.

General use of the System:
Hall, S. R., du Boulay, D. J. & Olthof-Hazekamp, R. (2000). Eds. Xtal3.7 System. University of Western Australia.

Individual calculations:
<<author name(s)>> (1999). <<program name>> Xtal3.7 System. Eds. S. R. Hall, D. J. du Boulay & R. Olthof-Hazekamp. University of Western Australia.

This version of Xtal is distributed under the GNU General Public License.