Changeset 5f3c534 in sasmodels for sasmodels/models/squarewell.py


Ignore:
Timestamp:
Mar 27, 2019 12:11:45 PM (5 years ago)
Author:
smk78
Branches:
master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests
Children:
9947865
Parents:
055ec4f
Message:

Tweaks to docs for all S(q) models as described in #1187

File:
1 edited

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  • sasmodels/models/squarewell.py

    r0507e09 r5f3c534  
    11# Note: model title and parameter table are inserted automatically 
    22r""" 
    3 This calculates the interparticle structure factor for a square well fluid 
    4 spherical particles. The mean spherical approximation (MSA) closure was 
    5 used for this calculation, and is not the most appropriate closure for 
    6 an attractive interparticle potential. This solution has been compared 
    7 to Monte Carlo simulations for a square well fluid, showing this calculation 
    8 to be limited in applicability to well depths $\epsilon < 1.5$ kT and 
    9 volume fractions $\phi < 0.08$. 
     3Calculates the interparticle structure factor for a hard sphere fluid  
     4with a narrow, attractive, square well potential. **The Mean Spherical  
     5Approximation (MSA) closure relationship is used, but it is not the most  
     6appropriate closure for an attractive interparticle potential.** However,  
     7the solution has been compared to Monte Carlo simulations for a square  
     8well fluid and these show the MSA calculation to be limited to well  
     9depths $\epsilon < 1.5$ kT and volume fractions $\phi < 0.08$. 
    1010 
    1111Positive well depths correspond to an attractive potential well. Negative 
    1212well depths correspond to a potential "shoulder", which may or may not be 
    13 physically reasonable. The stickyhardsphere model may be a better choice in 
    14 some circumstances. Computed values may behave badly at extremely small $qR$. 
     13physically reasonable. The :ref:`stickyhardsphere` model may be a better  
     14choice in some circumstances. 
     15 
     16Computed values may behave badly at extremely small $qR$. 
     17 
     18.. note:: 
     19 
     20   Earlier versions of SasView did not incorporate the so-called  
     21   $\beta(q)$ ("beta") correction [2] for polydispersity and non-sphericity.  
     22   This is only available in SasView versions 4.2.2 and higher. 
    1523 
    1624The well width $(\lambda)$ is defined as multiples of the particle diameter 
    … …  
    1826 
    1927The interaction potential is: 
    20  
    21   .. image:: img/squarewell.png 
    2228 
    2329.. math:: 
    … …  
    2935    \end{cases} 
    3036 
    31 where $r$ is the distance from the center of the sphere of a radius $R$. 
     37where $r$ is the distance from the center of a sphere of a radius $R$. 
    3238 
    33 In sasview the effective radius may be calculated from the parameters 
     39In SasView the effective radius may be calculated from the parameters 
    3440used in the form factor $P(q)$ that this $S(q)$ is combined with. 
    3541 
    … …  
    4652.. [#] R V Sharma, K C Sharma, *Physica*, 89A (1977) 213 
    4753 
     54.. [#] M Kotlarchyk and S-H Chen, *J. Chem. Phys.*, 79 (1983) 2461-2469 
     55 
    4856Source 
    4957------ 
    … …  
    5664* **Author:**  
    5765* **Last Modified by:**  
    58 * **Last Reviewed by:**  
     66* **Last Reviewed by:** Steve King **Date:** March 27, 2019 
    5967* **Source added by :** Steve King **Date:** March 25, 2019 
    6068""" 
    … …  
    6472 
    6573name = "squarewell" 
    66 title = "Square well structure factor, with MSA closure" 
     74title = "Square well structure factor with Mean Spherical Approximation closure" 
    6775description = """\ 
    6876    [Square well structure factor, with MSA closure] 
    69         Interparticle structure factor S(Q)for a hard sphere fluid with 
    70         a narrow attractive well. Fits are prone to deliver non-physical 
    71         parameters, use with care and read the references in the full manual. 
    72         In sasview the effective radius will be calculated from the 
    73         parameters used in P(Q). 
     77        Interparticle structure factor S(Q) for a hard sphere fluid  
     78    with a narrow attractive well. Fits are prone to deliver non- 
     79    physical parameters; use with care and read the references in  
     80    the model documentation.The "beta(q)" correction is available  
     81    in versions 4.2.2 and higher. 
    7482""" 
    7583category = "structure-factor" 
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