Analysis software (PD)

CMPR

1. CMPR doesn't read in my data

The maximum allowable number of data point read by CMPR is 20,000 by default. Download a copy of the read_xypair.tcl file and save it in the CMPR directory to alter this setting.

2. CMPR doesn't output GSAS file properly

CMPR has a default setting of 2 decimal places for the data step size, this must be increased to 3 to allow the observed data to plot properly, otherwise the observed pattern will appear to be compressed.  Download a copy of the write_gsas.tcl file and save it in the CMPR directory to alter this setting.

GSAS

1. I don't have a starting GSAS instrument file

GSAS uses an instrument file to define the relevant parameters pertaining to the diffraction instrumentation; an initial file which can be used as a starting point can be found here. 

Topas

1. I want to run Topas in interface mode, which text editor should i use?
We recommend that you use Jedit. It is a java-based text editor and a great deal of work has been done by other users to integrate it for use with Topas.
 
2. How do I set up Jedit?
 
An excellent tutorial to set up Jedit for use with Topas has been developed by John Evans of Durham University. It can be found here along with several other excellent tutorials for using Topas.

RIETICA

1. Rietica won't read my data

The error messages that Rietica reports don't necessarily tie in with the actual problem. So my suggestions are as follows:

  • The first problem will be that the memory is not large enough (i.e. the default setting reads only 10,000 points per histogram but the data files contain 22,000+). NOTE: if you have merged 2 data sets you will have >40,000 points which is in excess of what Rietica will handle, regardless.
    To change the limit per histogram to accommodate 1 dataset: launch Rietica and go to: File -> Preferences -> Memory, increase the 'Number of Data Points per Histogram' to the maximum no. (30,000) NOTE: you will need to exit and reopen Rietica for this to take effect.
     
  • Another problem may be that the folder and file name path is too long. It is therefore best to have the data in a folder not too far from the C-drive and to have a file name that is not too long.

2. What data step size do I use?

When you enter the 'Data step' value in Rietica it only needs to be approximate for xy data - e.g. 0.0039 - the reason is that the step sizes are uneven (which is the beauty of xy data) and Rietica can't possibly have you enter in each possible size. Even if you leave this field at zero Rietica will update the value to what it wants.

3. How do I construct a multi-histogram refinement?

Try opening one xy file to begin with (it is not necessary to have a file header but it should work with one also). After you have read 1 in successfully, in order to read more than one (i.e. a multiple histogram refinement) you will need to append (by copying and pasting) the second histogram to the end of the first file but you will need to have a line of text separating these or they won't read properly.

4. Why can't I use merged data instead of a multi-histogram refinement?

Multiple histograms must be used because at this stage Rietica will not read >30,000 points per histogram, and a merged data set (combining p1 & p2, for example) from the microstrip detector contains >40800 data points!

DIOPTAS

1. How can I get the correct calibrant for DIOPTAS?

The standard DIOPTAS software has old versions of the LaB6 and Si NIST Standard Reference Material (SRM) calibrant files.  The calibrant files for the newer SRMs can be found here and once downloaded must be placed the the 'calibrants' folder in the DIOPTAS directory.  The software must be re-started in order to use any newly added calibrants.