Changeset 500128b in sasmodels
- Timestamp:
- Jun 24, 2016 6:01:28 PM (8 years ago)
- 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:
- 59d94b3
- Parents:
- b3a85cd
- Location:
- sasmodels/models
- Files:
-
- 3 edited
Legend:
- Unmodified
- Added
- Removed
-
sasmodels/models/core_shell_parallelepiped.py
rec45c4f r500128b 6 6 can be different on all three (pairs) of faces.** 7 7 8 The form factor is normalized by the particle volume *V*such that8 The form factor is normalized by the particle volume $V$ such that 9 9 10 *I(q)* = *scale* \* <*f*\ :sup:`2`> / *V* + *background* 10 .. math:: 11 11 12 where < > is an average over all possible orientations of the rectangular solid. 12 I(q) = \text{scale}\frac{\langle f^2 \rangle}{V} + \text{background} 13 14 where $\langle \ldots \rangle$ is an average over all possible orientations 15 of the rectangular solid. 13 16 14 17 An instrument resolution smeared version of the model is also provided. … … 19 22 20 23 The function calculated is the form factor of the rectangular solid below. 21 The core of the solid is defined by the dimensions *A*, *B*, *C*such that22 *A* < *B* < *C*.24 The core of the solid is defined by the dimensions $A$, $B$, $C$ such that 25 $A < B < C$. 23 26 24 27 .. image:: img/core_shell_parallelepiped_geometry.jpg 25 28 26 There are rectangular "slabs" of thickness $t_A$ that add to the *A*dimension27 (on the *BC* faces). There are similar slabs on the *AC* $(=t_B)$ and *AB*28 $(=t_C)$ faces. The projection in the *AB*plane is then29 There are rectangular "slabs" of thickness $t_A$ that add to the $A$ dimension 30 (on the $BC$ faces). There are similar slabs on the $AC$ $(=t_B)$ and $AB$ 31 $(=t_C)$ faces. The projection in the $AB$ plane is then 29 32 30 33 .. image:: img/core_shell_parallelepiped_projection.jpg … … 43 46 44 47 **For the calculation of the form factor to be valid, the sides of the solid 45 MUST be chosen such that** *A* < *B* < *C*.48 MUST be chosen such that** $A < B < C$. 46 49 **If this inequality is not satisfied, the model will not report an error, 47 50 and the calculation will not be correct.** … … 49 52 FITTING NOTES 50 53 If the scale is set equal to the particle volume fraction, |phi|, the returned 51 value is the scattered intensity per unit volume ; ie, *I(q)* = |phi| *P(q)*.54 value is the scattered intensity per unit volume, $I(q) = \phi P(q)$. 52 55 However, **no interparticle interference effects are included in this calculation.** 53 56 … … 56 59 57 60 Constraints must be applied during fitting to ensure that the inequality 58 *A* < *B* < *C*is not violated. The calculation will not report an error,61 $A < B < C$ is not violated. The calculation will not report an error, 59 62 but the results will not be correct. 60 63 … … 64 67 based on the the averaged effective radius $(=\sqrt{(A+2t_A)(B+2t_B)/\pi})$ 65 68 and length $(C+2t_C)$ values, and used as the effective radius 66 for *S(Q)* when *P(Q)* \* *S(Q)*is applied.69 for $S(Q)$ when $P(Q) * S(Q)$ is applied. 67 70 68 71 .. Comment by Miguel Gonzalez: … … 71 74 72 75 To provide easy access to the orientation of the parallelepiped, we define the 73 axis of the cylinder using three angles |theta|, |phi| and |bigpsi|.76 axis of the cylinder using three angles $\theta$, $\phi$ and $\Psi$. 74 77 (see :ref:`cylinder orientation <cylinder-angle-definition>`). 75 The angle |bigpsi|is the rotational angle around the *long_c* axis against the76 *q* plane. For example, |bigpsi| = 0when the *short_b* axis is parallel to the78 The angle $\Psi$ is the rotational angle around the *long_c* axis against the 79 $q$ plane. For example, $\Psi = 0$ when the *short_b* axis is parallel to the 77 80 *x*-axis of the detector. 78 81 -
sasmodels/models/lamellar.py
rec45c4f r500128b 9 9 .. math:: 10 10 11 I(q) = scale*\frac{2\pi P(q)}{q^2\delta}11 I(q) = \text{scale}\frac{2\pi P(q)}{q^2\delta} + \text{background} 12 12 13 13 … … 16 16 .. math:: 17 17 18 P(q) = \frac{2\Delta\rho^2}{q^2}(1-cos(q\delta)) = \frac{4\Delta\rho^2}{q^2}sin^2(\frac{q\delta}{2}) 18 P(q) = \frac{2\Delta\rho^2}{q^2}(1-\cos(q\delta)) 19 = \frac{4\Delta\rho^2}{q^2}\sin^2\left(\frac{q\delta}{2}\right) 19 20 20 21 where $\delta$ is the total layer thickness and $\Delta\rho$ is the scattering length density difference. -
sasmodels/models/sc_paracrystal.py
rec45c4f r500128b 13 13 .. math:: 14 14 15 I(q) = \ frac{scale}{V_p}V_{lattice}P(q)Z(q)15 I(q) = \text{scale}\frac{V_\text{lattice}P(q)Z(q)}{V_p} + \text{background} 16 16 17 17 where scale is the volume fraction of spheres, $V_p$ is the volume of 18 the primary particle, $V_ {lattice}$ is a volume correction for the crystal18 the primary particle, $V_\text{lattice}$ is a volume correction for the crystal 19 19 structure, $P(q)$ is the form factor of the sphere (normalized), and 20 20 $Z(q)$ is the paracrystalline structure factor for a simple cubic structure. … … 28 28 .. math:: 29 29 30 V_ {lattice}=\frac{4\pi}{3}\frac{R^3}{D^3}30 V_\text{lattice}=\frac{4\pi}{3}\frac{R^3}{D^3} 31 31 32 32 The distortion factor (one standard deviation) of the paracrystal is included
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