[SasView Users] Sum Multi Function Version 4.2.2

Richard Heenan - UKRI STFC via users users at lists.sasview.org
Tue Apr 7 07:33:07 EDT 2020

Dear Karina,
I think that the answer for sasview 4.2.2 is "local monodisperse", the same S(Q) is used for all radii in a polydisperse form factor. The default addition of an S(Q) ties the radius used in the S(Q) to the mean radius from the P(Q).  Creating a P(Q)S(Q) product in the "plugin model" editor instead allows a different "effective radius" in the S(Q) to that from the P(Q)

>From sasview 4.3 we started to add some further functionality, which is now even further improved in sasview 5 where an option to include the beta(Q) decoupling approximation is introduced. This damps out oscillations due to S(Q) to allow at least approximately for the effects of polydispersity and/or non-spherical particle shapes. Sasview 5 also allows, where appropriate, for different choices of which radius  to use in the S(Q), for example for a cylinder, the half length, the radius or the diagonal radius.

For greater detail I would recommend downloading sasview 5 and reading the improved documentation in that version.

Richard Heenan

From: users [mailto:users-bounces at lists.sasview.org] On Behalf Of Abitaev, Karina via users
Sent: 07 April 2020 10:04
To: users at sasview.org
Subject: [SasView Users] Sum Multi Function Version 4.2.2

Dear Sasview Team,

I am using Sasview 4.2.2 to fit a colloidal crystal of polymer nanoparticles.
Here I use a Form factor for spheres, where a polydispersity is included. Furthermore, I am using a hard sphere structure factor.

I found the option to multiply the Spheres with hard spheres, so I can supply for each a radius and polydispersity. In this context I was wondering how the structure factor and form factor are combined (decoupling approximation, local monodisperse approx, ...)

Thank you in advance for your help!

Best wishes,


Karina Abitaev
Institut für Physikalische Chemie
Universität Stuttgart
Pfaffenwaldring 55
70569 Stuttgart

karina.abitaev at ipc.uni-stuttgart.de

Phone: +49 (0)711/685-64502
Fax: +49 (0)711/685-64443
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