Changeset 990c2eb in sasview


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Timestamp:
Apr 9, 2014 1:07:06 PM (10 years ago)
Author:
smk78
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
Message:

Updated by SMK

File:
1 edited

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  • src/sans/models/media/model_functions.rst

    rca1af82 r990c2eb  
    178178--------------- 
    179179 
    180 - EllipsoidModel 
    181 - CoreShellEllipsoidModel 
    182 - CoreShellEllipsoidXTModel 
     180- EllipsoidModel_ 
     181- CoreShellEllipsoidModel_ 
     182- CoreShellEllipsoidXTModel_ 
    183183- TriaxialEllipsoidModel 
    184184 
     
    21232123**2.1.26. CoreShellEllipsoidModel** 
    21242124 
    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  
     2125This model provides the form factor, *P(q)*, for a core shell ellipsoid (below) where the form factor is normalized by 
     2126the volume of the cylinder. 
     2127 
     2128*P(q)* = *scale* \* <*f*\ :sup:`2`> / *V* + *background* 
     2129 
     2130where the volume *V* = (4/3)\ |pi| (*r*\ :sub:`maj` *r*\ :sub:`min`\ :sup:`2`) and the averaging < > is applied over 
     2131all orientations for 1D. 
     2132 
     2133.. image:: img/image125.GIF 
    21322134 
    21332135The returned value is in units of |cm^-1|, on absolute scale. 
    21342136 
    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 
     2139The form factor calculated is 
     2140 
     2141.. image:: img/image126.PNG 
     2142 
     2143To provide easy access to the orientation of the core-shell ellipsoid, we define the axis of the solid ellipsoid using 
     2144two angles |theta| and |phi|\ . These angles are defined on Figure 2 of the CylinderModel_. The contrast is defined as 
     2145SLD(core) - SLD(shell) and SLD(shell) - SLD(solvent). 
     2146 
     2147In 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 
     2150NB: 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. 
    21572152 
    21582153==============  ========  ============= 
     
    21702165==============  ========  ============= 
    21712166 
    2172  
     2167.. image:: img/image127.JPG 
    21732168 
    21742169*Figure. 1D plot using the default values (w/1000 data point).* 
    21752170 
    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 
     2175Our model uses the form factor calculations implemented in a c-library provided by the NIST Center for Neutron Research 
     2176(Kline, 2006). 
    21842177 
    21852178REFERENCE 
    2186  
    2187 Kotlarchyk, M.; Chen, S.-H. J. Chem. Phys., 1983, 79, 2461. 
    2188  
    2189 Berr, S. J. Phys. Chem., 1987, 91, 4760. 
     2179M. Kotlarchyk, S.-H. Chen, *J. Chem. Phys.*, 79 (1983) 2461 
     2180S. J. Berr, *Phys. Chem.*, 91 (1987) 4760 
    21902181 
    21912182 
     
    22012192CoreShellEllipsoidModel. 
    22022193 
    2203 *2.1.27.1 Definition* 
     2194*2.1.27.1. Definition* 
    22042195 
    22052196.. image:: img/image125.gif 
     
    22572248**2.1.28. TriaxialEllipsoidModel** 
    22582249 
    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  
     2250This model provides the form factor, *P(q)*, for an ellipsoid (below) where all three axes are of different lengths, 
     2251i.e., *Ra* =< *Rb* =< *Rc*\ . **Users should maintain this inequality for all calculations**. 
     2252 
     2253*P(q)* = *scale* \* <*f*\ :sup:`2`> / *V* + *background* 
     2254 
     2255where 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 
    22692258 
    22702259The returned value is in units of |cm^-1|, on absolute scale. 
    22712260 
    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 
     2263The form factor calculated is 
     2264 
     2265.. image:: img/image129.PNG 
     2266 
     2267To provide easy access to the orientation of the triaxial ellipsoid, we define the axis of the cylinder using the 
     2268angles |theta|, |phi| and |bigpsi|. These angles are defined on Figure 2 of the CylinderModel_. The angle |bigpsi| is 
     2269the 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 
     2272The radius of gyration for this system is *Rg*\ :sup:`2` = (*Ra*\ :sup:`2` *Rb*\ :sup:`2` *Rc*\ :sup:`2`)/5. 
     2273 
     2274The contrast is defined as SLD(ellipsoid) - SLD(solvent). In the parameters, *semi_axisA* = *Ra* (or minor equatorial 
     2275radius), *semi_axisB* = *Rb* (or major equatorial radius), and *semi_axisC* = *Rc* (or polar radius of the ellipsoid). 
     2276 
     2277NB: 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 
     2279radius for *S(Q)* when *P(Q)* \* *S(Q)* is applied. 
    22932280 
    22942281==============  ========  ============= 
     
    23042291==============  ========  ============= 
    23052292 
    2306  
     2293.. image:: img/image130.JPG 
    23072294 
    23082295*Figure. 1D plot using the default values (w/1000 data point).* 
    23092296 
    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 
     2299Validation of our code was done by comparing the output of the 1D calculation to the angular average of the output of 
     23002D calculation over all possible angles. The Figure below shows the comparison where the solid dot refers to averaged 
     23012D while the line represents the result of 1D calculation (for 2D averaging, 76, 180, and 76 points are taken for the 
     2302angles of |theta|, |phi|, and |psi| respectively). 
     2303 
     2304.. image:: img/image131.GIF 
    23202305 
    23212306*Figure. Comparison between 1D and averaged 2D.* 
    23222307 
    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 
     2312Our model uses the form factor calculations implemented in a c-library provided by the NIST Center for Neutron Research 
     2313(Kline, 2006) 
    23292314 
    23302315REFERENCE 
    2331  
    2332 L. A. Feigin and D. I. Svergun Structure Analysis by Small-Angle X-Ray 
    2333 and Neutron Scattering, Plenum, New York, 1987. 
     2316L. A. Feigin and D. I. Svergun, *Structure Analysis by Small-Angle X-Ray and Neutron Scattering*, Plenum, 
     2317New York, 1987. 
    23342318 
    23352319 
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