All posts by DanielIrving (12)

topic: Joint refinement with individual Rwp  in the forum: Forums topas
DanielIrving #1
Member since Dec 2018 · 12 posts · Location: Southampton
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Perfect! I've altered the weightings on the PDF data and the R-factors appear to be a lot more realistic.

Thanks again for the help!
topic: Joint refinement with individual Rwp  in the forum: Forums topas
DanielIrving #2
Member since Dec 2018 · 12 posts · Location: Southampton
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Subject: Joint refinement with individual Rwp
Hi everyone,

I've recently started doing joint refinements of Bragg and PDF data and noticed that the Rwp seems to be a lot lower on the read out of TOPAS (typically around 3%) but was wondering how this value was calculated?

Also is there any way in a dual refinement like this to get the Rwp of each individual refinement?

Thanks for any help
Daniel
topic: Bragg + PDF Refinement  in the forum: Forums topas
DanielIrving #3
Member since Dec 2018 · 12 posts · Location: Southampton
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In reply to post ID 1969
Perfect! Thanks for uploading these.

Daniel
topic: Bragg + PDF Refinement  in the forum: Forums topas
DanielIrving #4
Member since Dec 2018 · 12 posts · Location: Southampton
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Subject: Bragg + PDF Refinement
Hi again,

I recently got hold of a copy of Rietveld Refinement: Practical Powder Diffraction Pattern Analysis Using TOPAS, and noticed that on the wiki that there is some example files for most chapters except chapter 11: Total scattering methods.

I am attempting to do simultaneous PDF and Bragg refinements and wondered if anyone had a copy of the example from the book or could point me in the direction of a tutorial for this before I start working on some real data.

Thanks in advance,

Daniel
topic: Adding Restraints for PDF Fittings  in the forum: Forums topas
DanielIrving #5
Member since Dec 2018 · 12 posts · Location: Southampton
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In reply to post ID 1949
That worked perfectly, the output CIF is no longer blowing up! Further to this, I was wondering if there was a way to add generic restraints e.g. all P-O-Al angles being around 145 degrees (+/-5 degrees), or do you have to set up individual restraints for each unique atom?

Thanks again!
topic: Adding Restraints for PDF Fittings  in the forum: Forums topas
DanielIrving #6
Member since Dec 2018 · 12 posts · Location: Southampton
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Subject: Adding Restraints for PDF Fittings
Hi everyone again,

I have another question that I'm unsure of and can't really find much information on currently so I'm hoping someone may know more about this. I am attempting to fit some PDF data of a zeolite to a CIF file (generated from a DFT lowest energy calculation), and I am trying to add restraints to this. I have been allowing the atomic positions to refine, which unsurprisingly, gives a good fit but an incredibly unlikely crystal structure.

I have looked at a few tutorials and forum posts that use the "Distance_Restrain" macro, and I have attempted to incorporate this into the calculation but the experimental fit appears to simply flat line. I am unsure to whether this is due to the way I have set up the restraint or whether that this particular restraint is only useful for structure solution. If the latter, is there any other way to apply this kind of restraint for PDF.

Sorry for the length of this post, but any help on the matter would be greatly appreciated!

Daniel
topic: Outputting .cif from PDF refinement  in the forum: Forums structure solution
DanielIrving #7
Member since Dec 2018 · 12 posts · Location: Southampton
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In reply to post ID 1943
That worked perfectly, thanks!
topic: Outputting .cif from PDF refinement  in the forum: Forums structure solution
DanielIrving #8
Member since Dec 2018 · 12 posts · Location: Southampton
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Subject: Outputting .cif from PDF refinement
Hi everyone,

I've been working on PDF refinements and was just wondering if there was a way to output the .cif of the sample that has been refined (i.e. lattice parameters and atomic positions) to check whether the structure has been refined sensibly. I've tried to use the various cif output macros etc. with no success. Any ideas?

Thanks in advance for any help!

Daniel
topic: Pair Distribution Function Analysis  in the forum: Forums structure solution
DanielIrving #9
Member since Dec 2018 · 12 posts · Location: Southampton
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In reply to post ID 1633
Hi,

I am also having an issue with the "weighted average of the scattering factors" input for the G(r) data and was wondering if anyone had a solution/could point me in the direction where I could obtain/calculate this factor.

Thanks in advance for any help!
topic: Macro Installation  in the forum: Forums topas
DanielIrving #10
Member since Dec 2018 · 12 posts · Location: Southampton
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In reply to post ID 1906
Got it all to work now! Thanks for all the help
topic: Macro Installation  in the forum: Forums topas
DanielIrving #11
Member since Dec 2018 · 12 posts · Location: Southampton
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In reply to post ID 1904
I've managed to install some of the macros now, but now having specific trouble with the Topas_for_PDF macro. I (think) have installed all the files in the right place ( pdf.insert.xml in the xinsert, pdf.inc in the main topas directory, and edited the local.inc file to include #include pdf.inc) and I still can't see the menu for PDF. I followed this tutorial (https://community.dur.ac.uk/john.evans/topas_workshop/tuto…) but I'm still having problems.

Thanks for any help!
topic: Macro Installation  in the forum: Forums topas
DanielIrving #12
Member since Dec 2018 · 12 posts · Location: Southampton
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Subject: Macro Installation
Hi,

I'm not sure if this is the correct place to put this. And also apologies in advance if this is a stupid question, as I have a very limited knowledge of coding.
I saw that TOPAS has the ability to import user made macros (from the wiki) to use within jEdit and TOPAS, but I cannot figure out how to actually install them. I was wondering if anyone could help out with this/point me in the direction of some kind of tutorial.

Thanks in advance!
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