XRS X-ray Rietveld System

The programs XRS-82, EXTRAC, DLS-76 and the supporting program KRIBER are available at www.kristall.ethz.ch/LFK/software/xrs

Supported operating systems are:

Unix
LINUX (Linux executables in file /pub/xrs-dist/linuxexe were kindly provided by Bernt Karasch of Ruhr-Universität Bochum, Germany. To run XRS-82 you also need the script `xrs' and some data files available in xrs-dist.tar.Z or xrs-dist.zip)
VMS
DOS
OS/2

XRS-82

The X-ray Rietveld System (XRS) comprises a collection of programs for crystal structural analysis with powder diffraction data. It provides routines at all levels of the analysis - examples are Fourier transforms and least-squares refinements, and also programs to aid in the interpretation and publication of the refined results. For details see xrs82/README and xrs82/manual/README and [1] for additional useful reading.

EXTRAC

A program to extract integrated intensities from powder diffraction data. This is done in a way described by A. Le Bail et al. [2] Individual intensities are extracted from the powder pattern by using a (..) cell- constrained whole pattern fitting program. The main originality of this program is that the individual F(obs) are not refined in a least-squares sense, they are estimated from an iterative procedure based on the very simple principle which gives the so called `F(obs)' in all Rietveld-type refinement programs. The idea behind EXTRAC was first introduced in [3].

EXTRAC is not a stand-alone program since it was derived from the XRS-82 program CRYLSP. To run EXTRAC you need modules from XRS-82. For details see extrac/README and extrac/manual/README.

DLS-76

A program for the simulation of crystal structures by geometric refinement.

For downlowding and/or the on-line DLS-76 Manual click here.

KRIBER

KRIBER is an interactive program to

calculate distances and angles,
generate input files for the program DLS-76 and for the program LOADAT of the X-Ray Rietveld System XRS-82, and
calculate coordination sequences and loop configurations.

For details see in subdirectory kriber/vms: program_description.txt, worked_example.txt and input_manual.

Further information

XRS-82, EXTRAC and DLS-76 represent old-fashioned FORTRAN-style programs. None of them will ever win a competition for the most user-friendly program. But all the programs do their job and have been used to refine several zeolite structures, including ZSM-5 and VPI-5.

You will find example input and output files for XRS-82, EXTRAC and DLS-76, but - sorry - no tutorial. The information included should be adequate to work your way through. In addition, feel free to ask for help on specific problems. We can not guarantee to help, but we will try.

References

[1] R.A. Young (editor) (1993). The Rietveld Method, Oxford University Press, UK.
[2] A. Le Bail, J.L. Fourquet, U. Bentrup (1992). J. Solid State Chemistry 100, 151-159.
[3] A. Le Bail, H. Duroy, J.L. Fourquet (1988). Mat. Res. Bull. 23, 447-452.

Ralf Grosse-Kunstleve. [email protected]