Changeset 990c2eb in sasview
- Timestamp:
- Apr 9, 2014 1:07:06 PM (11 years ago)
- Branches:
- master, ESS_GUI, ESS_GUI_Docs, ESS_GUI_batch_fitting, ESS_GUI_bumps_abstraction, ESS_GUI_iss1116, ESS_GUI_iss879, ESS_GUI_iss959, ESS_GUI_opencl, ESS_GUI_ordering, ESS_GUI_sync_sascalc, costrafo411, magnetic_scatt, release-4.1.1, release-4.1.2, release-4.2.2, release_4.0.1, ticket-1009, ticket-1094-headless, ticket-1242-2d-resolution, ticket-1243, ticket-1249, ticket885, unittest-saveload
- Children:
- 062ebef
- Parents:
- 12a1631
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-
- 1 edited
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src/sans/models/media/model_functions.rst
rca1af82 r990c2eb 178 178 --------------- 179 179 180 - EllipsoidModel 181 - CoreShellEllipsoidModel 182 - CoreShellEllipsoidXTModel 180 - EllipsoidModel_ 181 - CoreShellEllipsoidModel_ 182 - CoreShellEllipsoidXTModel_ 183 183 - TriaxialEllipsoidModel 184 184 … … 2123 2123 **2.1.26. CoreShellEllipsoidModel** 2124 2124 2125 This model provides the form factor, *P(q)*, for a core shell 2126 ellipsoid (below) where the form factor is normalized by the volume of 2127 the cylinder. P(q) = scale*<f^2>/V+background where the volume V= 2128 4pi/3*rmaj*rmin2 and the averaging < > is applied over all orientation 2129 for 1D. 2130 2131 2125 This model provides the form factor, *P(q)*, for a core shell ellipsoid (below) where the form factor is normalized by 2126 the volume of the cylinder. 2127 2128 *P(q)* = *scale* \* <*f*\ :sup:`2`> / *V* + *background* 2129 2130 where the volume *V* = (4/3)\ |pi| (*r*\ :sub:`maj` *r*\ :sub:`min`\ :sup:`2`) and the averaging < > is applied over 2131 all orientations for 1D. 2132 2133 .. image:: img/image125.GIF 2132 2134 2133 2135 The returned value is in units of |cm^-1|, on absolute scale. 2134 2136 2135 The form factor calculated is: 2136 2137 2138 2139 2140 2141 2142 2143 To provide easy access to the orientation of the coreshell ellipsoid, 2144 we define the axis of the solid ellipsoid using two angles , . 2145 Similarly to the case of the cylinder, those angles, and , are defined 2146 on Figure 2 of CylinderModel. 2147 2148 The contrast is defined as SLD(core) SLD(shell) or SLD(shell solvent). 2149 In the parameters, equat_core = equatorial core radius, polar_core = 2150 polar core radius, equat_shell = rmin (or equatorial outer radius), 2151 and polar_shell = = rmaj (or polar outer radius). 2152 2153 For P*S: The 2nd virial coefficient of the solid ellipsoid is 2154 calculate based on the radius_a (= polar_shell) and radius_b (= 2155 equat_shell) values, and used as the effective radius toward S(Q) when 2156 P(Q)*S(Q) is applied. 2137 *2.1.26.1. Definition* 2138 2139 The form factor calculated is 2140 2141 .. image:: img/image126.PNG 2142 2143 To provide easy access to the orientation of the core-shell ellipsoid, we define the axis of the solid ellipsoid using 2144 two angles |theta| and |phi|\ . These angles are defined on Figure 2 of the CylinderModel_. The contrast is defined as 2145 SLD(core) - SLD(shell) and SLD(shell) - SLD(solvent). 2146 2147 In the parameters, *equat_core* = equatorial core radius, *polar_core* = polar core radius, *equat_shell* = 2148 *r*\ :sub:`min` (or equatorial outer radius), and *polar_shell* = = *r*\ :sub:`maj` (or polar outer radius). 2149 2150 NB: The 2nd virial coefficient of the solid ellipsoid is calculated based on the *radius_a* (= *polar_shell*) and 2151 *radius_b* (= *equat_shell*) values, and used as the effective radius for *S(Q)* when *P(Q)* \* *S(Q)* is applied. 2157 2152 2158 2153 ============== ======== ============= … … 2170 2165 ============== ======== ============= 2171 2166 2172 2167 .. image:: img/image127.JPG 2173 2168 2174 2169 *Figure. 1D plot using the default values (w/1000 data point).* 2175 2170 2176 2177 2178 2179 2180 Figure. The angles for oriented coreshellellipsoid . 2181 2182 Our model uses the form factor calculations implemented in a c-library 2183 provided by the NIST Center for Neutron Research (Kline, 2006): 2171 .. image:: img/image122.JPG 2172 2173 *Figure. The angles for oriented CoreShellEllipsoid.* 2174 2175 Our model uses the form factor calculations implemented in a c-library provided by the NIST Center for Neutron Research 2176 (Kline, 2006). 2184 2177 2185 2178 REFERENCE 2186 2187 Kotlarchyk, M.; Chen, S.-H. J. Chem. Phys., 1983, 79, 2461. 2188 2189 Berr, S. J. Phys. Chem., 1987, 91, 4760. 2179 M. Kotlarchyk, S.-H. Chen, *J. Chem. Phys.*, 79 (1983) 2461 2180 S. J. Berr, *Phys. Chem.*, 91 (1987) 4760 2190 2181 2191 2182 … … 2201 2192 CoreShellEllipsoidModel. 2202 2193 2203 *2.1.27.1 Definition*2194 *2.1.27.1. Definition* 2204 2195 2205 2196 .. image:: img/image125.gif … … 2257 2248 **2.1.28. TriaxialEllipsoidModel** 2258 2249 2259 This model provides the form factor, *P(q)*, for an ellipsoid (below) 2260 where all three axes are of different lengths, i.e., Ra =< Rb =< Rc 2261 (Note that users should maintains this inequality for the all 2262 calculations). P(q) = scale*<f^2>/V+background where the volume V= 2263 4pi/3*Ra*Rb*Rc, and the averaging < > is applied over all orientation 2264 for 1D. 2265 2266 2267 2268 2250 This model provides the form factor, *P(q)*, for an ellipsoid (below) where all three axes are of different lengths, 2251 i.e., *Ra* =< *Rb* =< *Rc*\ . **Users should maintain this inequality for all calculations**. 2252 2253 *P(q)* = *scale* \* <*f*\ :sup:`2`> / *V* + *background* 2254 2255 where the volume *V* = (4/3)\ |pi| (*Ra* *Rb* *Rc*), and the averaging < > is applied over all orientations for 1D. 2256 2257 .. image:: img/image128.JPG 2269 2258 2270 2259 The returned value is in units of |cm^-1|, on absolute scale. 2271 2260 2272 The form factor calculated is: 2273 2274 2275 2276 To provide easy access to the orientation of the triaxial ellipsoid, 2277 we define the axis of the cylinder using the angles , andY. Similarly 2278 to the case of the cylinder, those angles, and , are defined on Figure 2279 2 of CylinderModel. The angle Y is the rotational angle around its own 2280 semi_axisC axis against the q plane. For example, Y = 0 when the 2281 semi_axisA axis is parallel to the x-axis of the detector. 2282 2283 The radius of gyration for this system is Rg2 = (Ra2*Rb2*Rc2)/5. The 2284 contrast is defined as SLD(ellipsoid) SLD(solvent). In the parameters, 2285 semi_axisA = Ra (or minor equatorial radius), semi_axisB = Rb (or 2286 major equatorial radius), and semi_axisC = Rc (or polar radius of the 2287 ellipsoid). 2288 2289 For P*S: The 2nd virial coefficient of the solid ellipsoid is 2290 calculate based on the radius_a (=semi_axisC) and radius_b 2291 (=sqrt(semi_axisA* semi_axisB)) values, and used as the effective 2292 radius toward S(Q) when P(Q)*S(Q) is applied. 2261 *2.1.28.1. Definition* 2262 2263 The form factor calculated is 2264 2265 .. image:: img/image129.PNG 2266 2267 To provide easy access to the orientation of the triaxial ellipsoid, we define the axis of the cylinder using the 2268 angles |theta|, |phi| and |bigpsi|. These angles are defined on Figure 2 of the CylinderModel_. The angle |bigpsi| is 2269 the rotational angle around its own *semi_axisC* axis against the *q* plane. For example, |bigpsi| = 0 when the 2270 *semi_axisA* axis is parallel to the *x*-axis of the detector. 2271 2272 The radius of gyration for this system is *Rg*\ :sup:`2` = (*Ra*\ :sup:`2` *Rb*\ :sup:`2` *Rc*\ :sup:`2`)/5. 2273 2274 The contrast is defined as SLD(ellipsoid) - SLD(solvent). In the parameters, *semi_axisA* = *Ra* (or minor equatorial 2275 radius), *semi_axisB* = *Rb* (or major equatorial radius), and *semi_axisC* = *Rc* (or polar radius of the ellipsoid). 2276 2277 NB: The 2nd virial coefficient of the triaxial solid ellipsoid is calculated based on the 2278 *radius_a* (= *semi_axisC*\ ) and *radius_b* (= sqrt(*semi_axisA* \* *semi_axisB*)) values, and used as the effective 2279 radius for *S(Q)* when *P(Q)* \* *S(Q)* is applied. 2293 2280 2294 2281 ============== ======== ============= … … 2304 2291 ============== ======== ============= 2305 2292 2306 2293 .. image:: img/image130.JPG 2307 2294 2308 2295 *Figure. 1D plot using the default values (w/1000 data point).* 2309 2296 2310 *Validation of the triaxialellipsoid 2D model* 2311 2312 Validation of our code was done by comparing the output of the 1D 2313 calculation to the angular average of the output of 2 D calculation 2314 over all possible angles. The Figure below shows the comparison where 2315 the solid dot refers to averaged 2D while the line represents the 2316 result of 1D calculation (for 2D averaging, 76, 180, 76 points are 2317 taken for the angles of theta, phi, and psi respectively). 2318 2319 2297 *2.1.28.2.Validation of the TriaxialEllipsoidModel* 2298 2299 Validation of our code was done by comparing the output of the 1D calculation to the angular average of the output of 2300 2D calculation over all possible angles. The Figure below shows the comparison where the solid dot refers to averaged 2301 2D while the line represents the result of 1D calculation (for 2D averaging, 76, 180, and 76 points are taken for the 2302 angles of |theta|, |phi|, and |psi| respectively). 2303 2304 .. image:: img/image131.GIF 2320 2305 2321 2306 *Figure. Comparison between 1D and averaged 2D.* 2322 2307 2323 2324 2325 Figure. The angles for oriented ellipsoid. 2326 2327 Our model uses the form factor calculations implemented in a c-library 2328 provided by the NIST Center for Neutron Research (Kline, 2006): 2308 .. image:: img/image132.JPG 2309 2310 *Figure. The angles for oriented ellipsoid.* 2311 2312 Our model uses the form factor calculations implemented in a c-library provided by the NIST Center for Neutron Research 2313 (Kline, 2006) 2329 2314 2330 2315 REFERENCE 2331 2332 L. A. Feigin and D. I. Svergun Structure Analysis by Small-Angle X-Ray 2333 and Neutron Scattering, Plenum, New York, 1987. 2316 L. A. Feigin and D. I. Svergun, *Structure Analysis by Small-Angle X-Ray and Neutron Scattering*, Plenum, 2317 New York, 1987. 2334 2318 2335 2319
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