Modeling Crystalline Nanosheets and Nanorods

[Julian Sarro]

Greetings PDF Community!

I'm a Master's student currently immersed in a project involving PDF Analysis with diffpy. My focus lies on a sample comprising crystalline nanosheets, purportedly measuring only 1 nm thick or spanning 1-3 unit cells. The assumption is that the crystals have grown along two specific crystallographic directions.

So far, I've utilized the sheetCF module (specifically, diffpy.srfit.pdf.characteristicfunctions) to model the thickness of the nanosheets. However, I'm curious if there's a method to incorporate crystallographic directions into the model as well.

I encounter a similar challenge with Nanorods, which exhibit growth primarily along one crystallographic direction.

Any assistance or insights would be greatly appreciated!

Cheers,
Julian

[Simon Billinge]

Dear Julian,

Yes, the best way to do this is to cut out a sheet from a 3D structure using a "cookie cutter" or some other method, then to use the debye scattering equation calculator to compute (and refine variables) from just the slab.

I am not sure where there is an example script.  If you can't find one, reach out and we can try and search.  Does anyone on the forum have an example they can share?

S

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Simon Billinge

Professor, 

Department of Applied Physics and Applied Mathematics

Columbia University

[Ratel-Ramond Nicolas]

Dear Julian,

Sorry for the late reply. Meantime,you may have found a solution to your issue. 

In case not, I have written a Python script that may help you. This script come with a user interface, documentation and tutorial. It allows you to:

- build crystalline nanoparticles from cif files: spheres, ellipsoids, rods and platelets are implemented

- build non crystalline nanoparticles (use of ase python library): icosahedron, decahedron, octahedron

- simulate PDF from structure files using Debye equation

- refine the structure to fit experimental PDF

This script and associated documentations can be downloaded at the following adress: https://github.com/nicoratel/WAXS_toolbox/tree/main

Your feedback is very welcome to help in the improvement of the software.

Best regards,

Nicolas

To view this discussion on the web visit https://groups.google.com/d/msgid/diffpy-users/CANugsUENBTdd4Qie7-sARchhuV2eLs%2B4zYmTn%2BaG%3DUN5vcZKaA%40mail.gmail.com.

[Simon Billinge]

Thanks Nicolas, this is really great!

To view this discussion on the web visit https://groups.google.com/d/msgid/diffpy-users/d688475f-7790-4430-b840-07b63f70c2aa%40gmail.com.

[Julian Sarro]

Hey Nicolas

Thanks for your answer. I will look into it.

Best

Julian