[SasView Users] Question on adding structure factors to a custom model

[Paul Butler via users]

Hi Mitchell,

So the answer to your basic question of combining several models in
different ways the answer is, I believe, yes (assuming I understand exactly
what you want to do).  Unfortunately there is a bug that prevents you from
using the Add/Multiply tool iteratively (and it does not allow combining
more than 2 models at once).  however you can use it to create for example
a sphere at squarewell and then use the Edit Custom Model to edit the file so
created.

Note the math has three (not just two) options: + which sums two models, *
which just multiplies two models and @ which multiplies assuming the the
second function is a structure factor (so provides some of the structure
factor features)

Doing so you will find several lines but the key one is this one:

model_info = load_model_info('sphere at hardsphere')

you can change this to be for example

model_info = load_model_info('powerlaw+sphere at hardsphere')

In principle you can do any number of these though you may want to be
careful about scale and background which are normally added outside the
parentheses.


That said, I'm not clear on your system. It sounds like you just have a
system of hard spheres that have formed a gel in which case I would
recommend either the Teixeira fractal, or, if you are looking at the liquid
glass transition from an attractive potential, maybe just spheres with the
Baxter potential? Of course if you have spheres in the "liquid" state in a
gel matrix (e.g. a polymer gel?) then I'm still not sure the solution you
sound like you are using is correct since the gel network would presumably
alter the effective interactions significantly?


Hope this helps


Stay safe

Paul





On Thu, Jul 14, 2022 at 10:00 AM Mitchell Kennedy via users <
users at lists.sasview.org> wrote:

> Good Morning. I am examining a system that has a combination of
> interacting spherical micelles, and a gel network. I am using the gel model
> and would love to add a spherical model with a squarewell potential
> structure factor. The only way I have found to do this is to add all three
> together as separate models, but this is not working very well. My question
> is, is it possible to add structure factors to custom models or to add a
> structure factor onto the spherical portion of the model where the radius
> is calculated using the sphere fitting parameters?
>
> Thank you for any help
> Mitchell Kennedy
> _______________________________________________
> users mailing list
> users at lists.sasview.org
> http://lists.sasview.org/cgi-bin/mailman/listinfo/users
>
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