Changeset 40a87fa in sasmodels for sasmodels/models/fuzzy_sphere.py
- Timestamp:
- Aug 8, 2016 11:24:11 AM (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:
- 2472141
- Parents:
- 2d65d51
- File:
-
- 1 edited
Legend:
- Unmodified
- Added
- Removed
-
sasmodels/models/fuzzy_sphere.py
r2c74c11 r40a87fa 1 1 r""" 2 For information about polarised and magnetic scattering, see 3 the :doc:`magnetic help <../sasgui/perspectives/fitting/mag_help>` documentation. 2 For information about polarised and magnetic scattering, see 3 the :doc:`magnetic help <../sasgui/perspectives/fitting/mag_help>` 4 documentation. 4 5 5 6 Definition 6 7 ---------- 7 8 8 The scattering intensity *I(q)*is calculated as:9 The scattering intensity $I(q)$ is calculated as: 9 10 10 11 .. math:: 11 I(q) = \frac{scale}{V}(\Delta \rho)^2 A^2(q) S(q) +\text{background} 12 13 I(q) = \frac{\text{scale}}{V}(\Delta \rho)^2 A^2(q) S(q) 14 + \text{background} 12 15 13 16 14 where the amplitude *A(q)*is given as the typical sphere scattering convoluted17 where the amplitude $A(q)$ is given as the typical sphere scattering convoluted 15 18 with a Gaussian to get a gradual drop-off in the scattering length density: 16 19 … … 18 21 19 22 A(q) = \frac{3\left[\sin(qR) - qR \cos(qR)\right]}{(qR)^3} 20 \exp\left(\frac{-(\sigma_ {fuzzy}q)^2}{2}\right)23 \exp\left(\frac{-(\sigma_\text{fuzzy}q)^2}{2}\right) 21 24 22 Here *|A(q)|*:sup:`2`\ is the form factor, *P(q)*. The scale is equivalent to the23 volume fraction of spheres, each of volume, *V*\. Contrast (|drho|) is the24 difference of scattering length densities of the sphere and the surrounding 25 s olvent.25 Here $A(q)^2$ is the form factor, $P(q)$. The scale is equivalent to the 26 volume fraction of spheres, each of volume, $V$. Contrast $(\Delta \rho)$ 27 is the difference of scattering length densities of the sphere and the 28 surrounding solvent. 26 29 27 Poly-dispersion in radius and in fuzziness is provided for, though the fuzziness 28 must be kept much smaller than the sphere radius for meaningful results. 29 30 30 Poly-dispersion in radius and in fuzziness is provided for, though the 31 fuzziness must be kept much smaller than the sphere radius for meaningful 32 results. 31 33 32 34 From the reference: 33 35 34 36 The "fuzziness" of the interface is defined by the parameter 35 |sigma| :sub:`fuzzy`\ . The particle radius *R*represents the radius of the37 $\sigma_\text{fuzzy}$. The particle radius $R$ represents the radius of the 36 38 particle where the scattering length density profile decreased to 1/2 of the 37 core density. The |sigma| :sub:`fuzzy`\is the width of the smeared particle39 core density. $\sigma_\text{fuzzy}$ is the width of the smeared particle 38 40 surface; i.e., the standard deviation from the average height of the fuzzy 39 41 interface. The inner regions of the microgel that display a higher density 40 42 are described by the radial box profile extending to a radius of 41 approximately *Rbox* ~ *R* - 2\ |sigma|\ . The profile approaches zero as42 *Rsans* ~ *R* + 2\ |sigma|\.43 approximately $R_\text{box} \sim R - 2 \sigma$. The profile approaches 44 zero as $R_\text{sans} \sim R + 2\sigma$. 43 45 44 46 For 2D data: The 2D scattering intensity is calculated in the same way as 1D, 45 where the *q*vector is defined as47 where the $q$ vector is defined as 46 48 47 .. math:: 48 49 q = \sqrt{{q_x}^2 + {q_y}^2} 50 49 .. math:: q = \sqrt{{q_x}^2 + {q_y}^2} 51 50 52 51 References
Note: See TracChangeset
for help on using the changeset viewer.