Some examples that should get you started with creating input files from scratch in jedit are given below. To run them easily you need to install the topas_durham macros. If you don’t already have these save the file linked here in your jedit .xinsert directory (normally c:\documents and settings\username\.jedit\xinsert). Then quit and restart jedit. These macros just contain the subset of topas instructions that you’ll need for these simple examples. These are meant as quick demonstrations only – not “text book” examples of how to do a Rietveld refinement! More detailed tutorials are available via the link on the menu on the left.
1. A simple lab Rietveld refinement.
Save the following files in a directory which are for an lab X-ray data collection on TiO2:
Launch jedit. All the instructions you need to perform a simple Rietveld refinement are in the “Simple Rietveld Refinement” menu. Click on the “Select Data File” button and browse to select d5_05005.raw. In the “Instrument/Corrections” folder click to select “Durham_d5000_scint”, the diffractomerter used to collect the data. Click on “Refine zero point”. In the “Structure – cif” folder click on “Read a CIF file” and browse to select rutile.cif.
Click on the button “->TA” to save the file and tell topas academic this is the file you want to refine on. The file will automatically be given a sensible name/extension. You can change this if you want.
In topas academic hit the “run” button (a triangle pointing to the right like play on an old tape recorder!). On completion go back to jedit and the input file will have been been updated.
Refine temperature factors by adding the phrase “beq @ 0” at the end of each site line. N.B. you can do this quickly in jedit by column highlighting the end of each line then typing….the text you type will appear on each line simultaneously. Then try giving the O1 x and y coordinates the same parameter name and refining them. i.e. change the line to read:
site O1 x xo1 0.30600 y xo1 0.30600 z 0.00000 occ O 1.00000 beq @ 0.1064`
2. A Simple Time of Flight Refinement
Save the following files in a directory:
The xye file is a time of flight data set recorded on HRPD at the isis pulsed neutron source. If you click through the various headings under “Simple tof Rietveld” you should be able to perform a simple Rietveld fit to the data.
3. A Simple Pawley Refinement
Save the following file in a directory:
The data were recorded on the Durham d5000 using variable slits on a sample of Y2O3. The cell parameter is around 10.6 Angstroms and space group is Ia-3. By clicking through the headings under the “Simple Pawley Refinement” folder you should be able to fit the data and get an R-factor around 4.5% without changing any of the refinement settings.