general core-shell model

[marimperorclerc]

We are currently dealing with faceted nanoparticles containing some seed inside.

Both the seed and the whole particle are polyhedrons, as represented here:

Interestingly, the seed center is sometimes shifted from the center of the overall particle.
And SLDs are different in the core and in the shell regions.

So I'm wondering if writing a general core-shell model would be useful ?
It would apply to any kind of core-shell object and call any two already existing models, one for the core, and a second one for the whole particle.

So, instead or rewriting a core-shell version for any combination of interest, we could use a general model.
And it might be easier to do it this way.

It would combine the form factor amplitudes (Fqabc_in(qa,qb,qc) and Fqabc_out(qa,qb,qc)) together.
With the appropriate SLD combinations as usual.

Plus the possibility to shift the origins of the two shapes and to rotate them from each other to match the description of the core-shell particle.

The implementation might be something similar to the sum of two models, but adding amplitudes and not intensities.