Changeset bf227cd in sasmodels for sasmodels/models/mono_gauss_coil.py

Timestamp:

Mar 16, 2016 3:40:01 PM (8 years ago)

Author:

smk78

Branches:

master, core_shell_microgels, costrafo411, magnetic_model, release_v0.94, release_v0.95, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

a1c91c2

Parents:

cb97bff

Message:

Improved

File:

• sasmodels/models/mono_gauss_coil.py (modified) (5 diffs)

sasmodels/models/mono_gauss_coil.py

@@ -8 +8 @@
 This model strictly describes the scattering from *monodisperse* polymer chains in theta solvents or polymer melts, conditions under which the distances between segments follow a Gaussian distribution. Provided the number of segments is large (ie, high molecular weight polymers) the single-chain form factor P(Q) is that described by Debye (1947).
 
-To describe the scattering from *polydisperse* polymer chains, see the poly_gauss_coil model.
+To describe the scattering from *polydisperse* polymer chains, see the To describe the scattering from *monodisperse* polymer chains, see the :ref:`poly_gauss_coil <poly-gauss-coil>` model.
 
 Definition
 ----------
 
-     *I(q)* = *scale* |cdot| *P(q)* + *background*
+     *I(q)* = *scale* |cdot| *I* \ :sub:`0` |cdot| *P(q)* + *background*
          
 where
 
-     *scale* = |phi|\ :sub:`poly` |cdot| *V* |cdot| (|rho|\ :sub:`poly` - |rho|\ :sub:`solv`)\  :sup:`2`
+     *I*\ :sub:`0` = |phi|\ :sub:`poly` |cdot| *V* |cdot| (|rho|\ :sub:`poly` - |rho|\ :sub:`solv`)\  :sup:`2`
 
      *P(q)* = 2 [exp(-Z) + Z - 1] / Z \ :sup:`2`
@@ -28 +28 @@
          
 Here, |phi|\ :sub:`poly` is the volume fraction of polymer, *V* is the volume of a polymer coil, *M* is the molecular weight of the polymer, *N*\ :sub:`A` is Avogadro's Number, |delta| is the bulk density of the polymer, |rho|\ :sub:`poly` is the sld of the polymer, |rho|\ :sub:`solv` is the sld of the solvent, and *R*\ :sub:`g` is the radius of gyration of the polymer coil.
-
-.. figure:: img/mono_gauss_coil_1d.jpg
-
-    1D plot using the default values.
 
 The 2D scattering intensity is calculated in the same way as the 1D, but where the *q* vector is redefined as
@@ -59 +55 @@
 
 #             ["name", "units", default, [lower, upper], "type", "description"],
-parameters =  [["radius_gyration", "Ang", 50.0, [0.0, inf], "", "Radius of gyration"]]
+parameters =  [["i_zero", "1/cm", 1.0, [-inf, inf], "", "Intensity at q=0"],
+               ["radius_gyration", "Ang", 50.0, [0.0, inf], "", "Radius of gyration"]]
 
 # NB: Scale and Background are implicit parameters on every model
@@ -68 +65 @@
        inten = 1.0
     else:
-       inten = 2.0 * (exp(-z) + z - 1.0 ) / (z * z)
+       inten = i_zero * 2.0 * (exp(-z) + z - 1.0 ) / (z * z)
     return inten
 Iq.vectorized =  True  # Iq accepts an array of q values
@@ -78 +75 @@
 
 demo =  dict(scale = 1.0,
+            i_zero = 1.0,
             radius_gyration = 50.0,
             background = 0.0)