Merge pull request #603 from SasView/602-fcc-paracrystalline-model-fix

602: Fix FCC Paracrystal Lattice Parameter Calculation
SasView · Jul 17, 2024 · 39c41ab · 39c41ab
2 parents d20724b + a09344e
commit 39c41ab
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diff --git a/sasmodels/models/fcc_paracrystal.c b/sasmodels/models/fcc_paracrystal.c
@@ -5,7 +5,7 @@ fcc_Zq(double qa, double qb, double qc, double dnn, double d_factor)
     const double a1 = ( qa + qb)/2.0;
     const double a2 = ( qa + qc)/2.0;
     const double a3 = ( qb + qc)/2.0;
-    const double d_a = dnn/sqrt(2);
+    const double d_a = dnn*sqrt(2);
 
     // Matsuoka 23-24-25
     //     Z_k numerator: 1 - exp(a)^2

diff --git a/sasmodels/models/fcc_paracrystal.py b/sasmodels/models/fcc_paracrystal.py
@@ -213,9 +213,10 @@ def random():
 #
 # October 26, 2022, PDB fixed unit tests to conform to new maths
 # TODO: fix the 2d tests
-q = 4.*pi/220.
+# Test position of first Bragg Peak at q = 2.0 * pi * np.sqrt(3) / (np.sqrt(2) * 220)
+q=0.035
 tests = [
-    [{}, [0.001, q, 0.25], [1.9839734995338474, 0.3352457353010224, 0.005804136688760973]],
+    [{}, [0.01, q, 0.25], [0.0213498915484313, 69.03586722100925, 0.005713137547083953]],
     #[{}, (-0.047, -0.007), 238.103096286],
     #[{}, (0.053, 0.063), 0.863609587796],
 ]