How to speed up sequential refinements

jlstapper

Hello,

This is a question about multiple consecutive refinements for a time-dependent XRD study. We have datasets of in situ XRD scans of a mineral reaction which each consists of a very large number of scans (several 100s or >1000). I have an .inp file that does the sequential refinement, but as it continues through all the scans, the process gets progressively slower. I wonder if anyone has come across this feature and knows any solution?

I have a feeling it's because Topas stores the data for every single refinement and adds it to the plot in the GUI, so if anyone knows a way to suppress this output, that would also be a good way to start!

Please let me know your thoughts and, if necessary, I can share the .inp file I'm working with.

Thank you!

rowlesmr

What is the model starting point for each of the scans? If you are starting each scan from the same point, then the model probably has to move further each time to get to the (global?) minimum.

jlstapper

Thank you both for the advice!

rowlesmr I am using an initial input based on a detailed XRD scan of the material before it goes into the sample cell. The code also contains the line
"out_file = Concat(String(INP_File), ".INP");
which should make sure that the output of each refinement is used as the input for the next one.

johnsoevans Thank you for these tips, I will try the analyses again using "gui_ignore". It looks like this command should follow "xdd" but I am using the XY macro for choosing the subsequent files. Should I nest the "gui_ignore" command in a modified version of this XY macro?

Kind regards,
Julian

johnsoevans

The gui update will slow things down a little. You notice this if you're e.g. doing simulated annealing: if you minimise the window temporarily the number of iters per second goes up significantly. The same trick might help here.

I can typically go through a few thousand patterns without problems. However, if you don't want to examine the fits in topas, you could put the command "gui_ignore" in the xdd section. If you're using #list you can probably set things up so that e.g. every 10th pattern gets plotted. There will be some other tricks round this in future topas releases.

The other option is to use tc.exe and run things without graphics from the command prompt.

johnsoevans

I think it can go anywhere in an xdd section.