• General data treatment at ILL
• 0. Detector calibration and data monitoring
• 1. Retrieve and file data
• 2. Data analysis
• 3. Crystallography

Here

Monitoring of the actual data acquisition (live display) are effectuated by /users/mad/GUI/SPY/XSPY.out on the instrument control SGI d20.ill.fr or with the Macintosh Live Display at the Instrument Control.

Detector calibaration is effectuated during read-in of data by LAMP by default of if you called the macro flag,/noeff (unless un un-set the flag with flag,/noeff).

Monitoring of already saved data (numors) may be performed by LAMP, by the function monit().

If you want to see directly your data numor files, look for them on /hosts/d20/users/data/ (immediate storage on the instrument control machine), /hosts/d20sgi/data/data/d20/d20_?/ (local storage on the data treatment machine after frequent transfer) or /usr/illdata/data/d20/D20_?/ (central storage on the ILL file server after less frequent transfer).

In LAMP you may read and visualize your numor data, perform more or less simple arithmetic oprerations of the read-in workspaces by using the read-in window, the formula editors or even the macro editor (it depends on the complexity of your needs). Also try to take advantage of the 'Selector Access' on the left-hand side of the 'Read' button!

If you like to read in other data than numors, try to use the 'Read and Restore Workspaces' window by clicking the button on the left of the LAMP main window below the 'Selector Access'! It allows you to read in several ASCII and binary data formats.

In the IDL macro language commands like open, print, read and close exist in order to perform more complicate and user-adapted read- and write-tasks. Use of the formula editor or the macro editor depends on the needed complexity. Type '? &' in the formula editor in order to start an IDL-help window that explains all features of IDL - in fact, it's the hypertext version of the complete IDL handbook. Remember that LAMP itself is written in the IDL macro language by ILL computing staff!

You may export your pretreated data by using the 'Export' window (click on the button right of the 'Read and Restore Workspaces' button). It will write your workspaces in ASCII or binary format, exploitable by LAMP. Use the 'exriet' procedure from a formula window in order to write two Rietveld data files from your workspace, one for fullprof and the other for the gsas program. If you need other formats, ask the instrument responsible or try to write your own little IDL macro!

Most of the following programs run on every Silicon Graphics workstation of the Diffraction Group, simply type the name of the program in small letters and return. Common programs are stored on /usr1/local/bin, documentations in /usr1/local/doc.

absor

B. Ouladdiaf, ILL 1997

A program for calculating the absorption coefficients for annular cylinder (also standard cylinder) is running now on the sgi. To run it, type absor, and you need to enter the linear absorption coefficient µR, the radius ratio and the angular range. A mathematica module for the same calculation is also available. Mathematica is running on jade.ill.fr (the mathematica version is slower). Note that the absorption correction for annular cylinder is very different from that of standard cylinder. A gain of factor of 5 in transmission can be obtained at low angle for the same amount of sample.

fit.pro

Multiple peak fit (multiple diagrams) - D20 LAMP-macro under development
by T. Hansen, ILL

PKFit

Peak fitting, mainly for Three-Axis-Spectrometers
by A. Filhol, ILL

ABFFit

Fit pattern with a background + mathematical function (e.g. gaussian). Can be run in automatic mode to analyse sequences of patterns. Results of such sequential refinements can be visualized by DISABF.

XRFit

Single peak fit

A script for treating multiple diagrams exists:
xrin & xrcyc, by B.Ouladdiaf, ILL.

FitFun

An Interactive and Graphical Fitting Routine
by R. Ghosh, ILL

The Rietveld Method

If you want to continue your data treatment at home on a PC or on a Mac, have a look on this List of Rietveld Software.

STRAP

A general system to analyse individual diffraction patterns or sets of sequential data (time- or temperature-resolved powder diffraction experiments). Three levels of data analysis are available in this system:

• numerical analysis : fit pattern (or part of it) with a mathematical function (peak + background) without assuming any physical model for the diffraction proccess.
• cell constrained profile refinement : used to extract refined cell parameters and intensities when the symmetry and approximate cell parameters are known. This program does not require a structural model.
• profile fitting structure refinement (Rietveld refinement) : fit the powder pattern using the instrument characteristics (resolution curve) and the structural parameters of the sample as variables.

For more information, see the STRAP manual (ILL- internal report 87RO14T).

FullProf

Profile refinement program by Juan Rodriguez-Carvajal, LLB, Saclay (Paris) based on DBWS of Young & Wiles). Here you'll find the most recent version of fullprof for your platform. On the Diffraction Group computers you'll find three versions of fullprof: fp (3.0), fullprof (3.2) and fp35 (3.5).

Includes :

• cell constrained profile refinement
• profile structure refinement (Rietveld refinement) of nuclear and magnetic structures, as well as a number of new features

A script for sequential refinements (thermodiffractometry) exists:
fpin & fpcyc, by Bachir Ouladdiaf, ILL.

GSAS

"General Structure Analysis System" by A. C. Larson & Robert B. Von Dreele, LANSCE, Los Alamos

Includes :

• cell constrained profile refinement
• profile structure refinement (Rietveld) of nuclear and magnetic structures as well as a number of new features

A script for sequential refinements has been written by Paolo Radaelli, ILL.

XND

Rietveld Structure Refinement, available at ftp://rx-crg1.polycnrs-gre.fr/dist/xnd , manual at http://rx-crg1.polycnrs-gre.fr/public/xnd/xnd.html. Author :J.-François Bérar, Laboratoire de Cristallographie - CNRS, BP 166, 38042 Grenoble CEDEX 09, France, E-mail : berar(at)polycnrs-gre.fr

Features

• Incommensurate and modulated Structures
• Multiple datasets
• Varying temperature

Magnetic structures are not implemented yet. Nevertheless it might be the ideal treatment of time-resolved data or thermodiffractometries, as it treats the ensemble of data and not each acquisition sequentially. Of course, you need a starting model (linear, parabolic etc.) of the time- pressure-, or temperature-dependency of all varying parameters.

sgi

Utility for spacegroup information - try it!

index

Gives 2theta etc. of Bragg peaks for known unit cells.

treor

Powder indexation

dicvol

Powder indexation

celref

refine cell parameters from a list h,k,l 2-theta (i.e. from the output of ABFFit)

LAZY PULVERIX

User friendly program to calculate a powder diffraction pattern (useful to prepare a diffraction experiment). Note that FullProf can performe the same task.

BONDLA

Calculate bond lengths and angles and their esd's.

SHELX

Probably the most commonly used structure refinement program. Normally used for structure determination and refinement from single crystal data, it may also be useful in some cases to analyse powder data (e.g. after using Pawley's program to determine a structural model by direct methods).

SIRPOW

Structure determination from powder data, very powerfull

Cerius2

Molecular Simulations Package by MSI
Usefull for 'visual' structure solution (Rietveld refinement by DBWS or GSAS, indexation by TREOR or DICVOL and many others ...) and Force Field calculations.

ORTEP

Old standard to illustrate crystal structures.

STRUPLO

Prepares a polyhedral representation of a structure (octahedra & tetrahedra)

SCHAKAL

Graphical representation of molecular models (stick & ball)

Last updated 08 March 2000 by Thomas C Hansen