Changeset 5f3c534 in sasmodels for sasmodels/models/hardsphere.py

Timestamp:

Mar 27, 2019 10:11:45 AM (5 years ago)

Author:

smk78

Branches:

master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

9947865

Parents:

055ec4f

Message:

Tweaks to docs for all S(q) models as described in #1187

File:

• sasmodels/models/hardsphere.py (modified) (4 diffs)

sasmodels/models/hardsphere.py

@@ -1 +1 @@
 # Note: model title and parameter table are inserted automatically
-r"""Calculate the interparticle structure factor for monodisperse
+r"""
+Calculates the interparticle structure factor for monodisperse
 spherical particles interacting through hard sphere (excluded volume)
-interactions.
-May be a reasonable approximation for other shapes of particles that
-freely rotate, and for moderately polydisperse systems. Though strictly
-the maths needs to be modified (no \Beta(Q) correction yet in sasview).
+interactions. This $S(q)$ may also be a reasonable approximation for 
+other particle shapes that freely rotate (but see the note below), 
+and for moderately polydisperse systems.
+
+.. note::
+
+   This routine is intended for uncharged particles! For charged 
+   particles try using the :ref:`hayter-msa` $S(q)$ instead.
+   
+.. note::
+
+   Earlier versions of SasView did not incorporate the so-called 
+   $\beta(q)$ ("beta") correction [1] for polydispersity and non-sphericity. 
+   This is only available in SasView versions 4.2.2 and higher.
 
 radius_effective is the effective hard sphere radius.
 volfraction is the volume fraction occupied by the spheres.
 
-In sasview the effective radius may be calculated from the parameters
+In SasView the effective radius may be calculated from the parameters
 used in the form factor $P(q)$ that this $S(q)$ is combined with.
 
 For numerical stability the computation uses a Taylor series expansion
-at very small $qR$, there may be a very minor glitch at the transition point
-in some circumstances.
+at very small $qR$, but there may be a very minor glitch at the 
+transition point in some circumstances.
 
-The S(Q) uses the Percus-Yevick closure where the interparticle
-potential is
+This S(q) uses the Percus-Yevick closure relationship [2] where the 
+interparticle potential $U(r)$ is
 
 .. math::
@@ -27 +38 @@
     \end{cases}
 
-where $r$ is the distance from the center of the sphere of a radius $R$.
+where $r$ is the distance from the center of a sphere of a radius $R$.
 
 For a 2D plot, the wave transfer is defined as
@@ -38 +49 @@
 References
 ----------
+
+.. [#] M Kotlarchyk & S-H Chen, *J. Chem. Phys.*, 79 (1983) 2461-2469
 
 .. [#] J K Percus, J Yevick, *J. Phys. Rev.*, 110, (1958) 1
@@ -63 +76 @@
     [Hard sphere structure factor, with Percus-Yevick closure]
         Interparticle S(Q) for random, non-interacting spheres.
-    May be a reasonable approximation for other shapes of
-    particles that freely rotate, and for moderately polydisperse
-        systems. Though strictly the maths needs to be modified -
-    which sasview does not do yet.
+    May be a reasonable approximation for other particle shapes
+    that freely rotate, and for moderately polydisperse systems
+    . The "beta(q)" correction is available in versions 4.2.2
+    and higher.
     radius_effective is the hard sphere radius
     volfraction is the volume fraction occupied by the spheres.