A Rietveld Refinement Program for
Real Time Powder Diffraction Patterns
XND, Release 1.10
Revised on June, 26th 1995
Document not finished, please use the old
xnd_doc.d file as
the complete reference manual.
Contents
The program
Users Files
Usage and related info
Examples
- Constrained refinement codes
- Examples files
Installation and structure of the program
- Installation guide.
- Structure of the program.
The program XND is devoted to the refinement of crystal structures
starting from powder diffraction patterns. The structure refinement is
carried out through the Rietveld (1969) method. The aim of the program is to
provide an easy approach to the treatment of multiple diffraction patterns
arising from a large number of physical and chemical problems
as the study of phase transition and in the real time monitoring of reactions.
The source of the program is written in standard C language and
great care has been taken to allow an easy implementation on different
computer platforms. The present version can run on most of Unix stations
(Sun, HP, IBM ...) and on
PC compatibles (80286 or higher), it was also run on Powermac and on VAX.
The main features of this version are:
- multiple wavelenghts;
- X-ray, Synchrotron and neutron (constant wavelength) powder patterns;
- joint refinement of X-ray and Neutron powder data;
- mono-incommensurate displacive and substitutional modulated
structures;
- pattern matching of diffracted intensities whithout a priori
knowledge of the crystal structure.
- choice of the weighting scheme;
- spline or interpolation of background;
- no soft limit to the number of phases;
- preferred orientation functions defined in the reciprocal lattice;
- profile functions defined in the reciprocal lattice;
- treatment of profile asymmetry;
- rigid body constraints;
- penalties on bond lenghts.
The first description of this program was presented at the I.U.Cr. Sat.
Meeting, "Powder Diffractometry" kept in Toulouse in July 1990
(Bérar,1990).
Numerous people have been concerned by previous releases and have
participated to the debugging.
The incommensurate modulation were introduced for friends in my
previous laboratory ( CPS-ECP); D. Grebille (CRISMAT) and
G. Baldinnozzi (ECP) have corrected the calculation of the
satelites. GB is also responsable for some improvments in
the documentation being at the origin of the new document.
J.-François Bérar
Laboratoire de Cristallographie - CNRS,
BP 166, 38042 Grenoble CEDEX 09, France
e-mail: berar@rx-crg1.polycnrs-gre.fr