# Changeset db1d9d5 in sasmodels for sasmodels/models/rpa.py

Ignore:
Timestamp:
Mar 28, 2019 5:16:51 PM (9 months ago)
Branches:
master, ticket-1257-vesicle-product, ticket_1156, ticket_822_more_unit_tests
Children:
8795b6f
Parents:
a34b811
Message:

merge with master

File:
1 edited

### Legend:

Unmodified
 r0507e09 These case numbers are different from those in the NIST SANS package! The models are based on the papers by Akcasu *et al.* and by Hammouda assuming the polymer follows Gaussian statistics such The models are based on the papers by Akcasu *et al.*  and by Hammouda  assuming the polymer follows Gaussian statistics such that $R_g^2 = n b^2/6$ where $b$ is the statistical segment length and $n$ is the number of statistical segment lengths. A nice tutorial on how these are constructed and implemented can be found in chapters 28 and 39 of Boualem Hammouda's 'SANS Toolbox'. constructed and implemented can be found in chapters 28, 31 and 34, and Part H, of Hammouda's 'SANS Toolbox' . In brief the macroscopic cross sections are derived from the general forms for homopolymer scattering and the multiblock cross-terms while the inter In brief, the macroscopic cross sections are derived from the general forms for homopolymer scattering and the multiblock cross-terms while the inter, polymer cross terms are described in the usual way by the $\chi$ parameter. * **Component D is assumed to be the "background" component (ie, all contrasts are calculated with respect to component D).** So the scattering contrast for a C/D blend = [SLD(component C) - SLD(component D)]\ :sup:2. for a C/D blend $\rho_{C/D} = [\rho_C - \rho_D]$\ :sup:2. * Depending on which case is being used, the number of fitting parameters can vary. * **Converted to sasmodels by:** Paul Kienzle **Date:** July 18, 2016 * **Last Modified by:** Paul Butler **Date:** March 12, 2017 * **Last Reviewed by:** Paul Butler **Date:** March 12, 2017 * **Last Reviewed by:** Steve King **Date:** March 27, 2019 * **Source added by :** Steve King **Date:** March 25, 2019 """