Changeset c78d677 in sasmodels


Ignore:
Timestamp:
Sep 28, 2018 10:31:31 AM (3 months ago)
Author:
smk78
Branches:
master, beta_approx, cuda-test, py3, ticket-1015-gpu-mem-error, ticket-1015-quick-fix, ticket-1157, ticket-608-user-defined-weights, ticket_1156
Children:
c351383
Parents:
9235fc3
Message:

Fixed inline substitution errors & improved formatting and presentation

File:
1 edited

Legend:

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Added
Removed
  • sasmodels/models/be_polyelectrolyte.py

    r9235fc3 rc78d677  
    11r""" 
     2.. note:: Please read the Validation section below. 
     3 
    24Definition 
    35---------- 
     
    2022 
    2123$K$ is the contrast factor for the polymer which is defined differently than in 
    22 other models and is given in barns where $1 barn = 10^{-24} cm^2$.  $K$ is 
     24other models and is given in barns where 1 $barn = 10^{-24}$ $cm^2$.  $K$ is 
    2325defined as: 
    2426 
     
    2931    a = b_p - (v_p/v_s) b_s 
    3032 
    31 where $b_p$ and $b_s$ are sum of the scattering lengths of the atoms 
    32 constituting the monomer of the polymer and the sum of the scattering lengths 
    33 of the atoms constituting the solvent molecules respectively, and $v_p$ and 
    34 $v_s$ are the partial molar volume of the polymer and the solvent respectively 
    35  
    36 $L_b$ is the Bjerrum length(|Ang|) - **Note:** This parameter needs to be 
    37 kept constant for a given solvent and temperature! 
    38  
    39 $h$ is the virial parameter (|Ang^3|) - **Note:** See [#Borue]_ for the 
    40 correct interpretation of this parameter.  It incorporates second and third 
    41 virial coefficients and can be Negative. 
    42  
    43 $b$ is the monomer length(|Ang|), $C_s$ is the concentration of monovalent 
    44 salt(1/|Ang|- converted from mol/L), $\alpha$ is the ionization degree 
    45 (ionization degree : ratio of charged monomers  to total number of monomers), 
    46 $C_a$ is the polymer molar concentration(1/|Ang|- converted from mol/L), 
    47 and $background$ is the incoherent background. 
     33where: 
     34 
     35- $b_p$ and $b_s$ are **sum of the scattering lengths of the atoms** 
     36  constituting the polymer monomer and the solvent molecules, respectively. 
     37 
     38- $v_p$ and $v_s$ are the partial molar volume of the polymer and the  
     39  solvent, respectively. 
     40 
     41- $L_b$ is the Bjerrum length (|Ang|) - **Note:** This parameter needs to be 
     42  kept constant for a given solvent and temperature! 
     43 
     44- $h$ is the virial parameter (|Ang^3|) - **Note:** See [#Borue]_ for the 
     45  correct interpretation of this parameter.  It incorporates second and third 
     46  virial coefficients and can be *negative*. 
     47 
     48- $b$ is the monomer length (|Ang|). 
     49 
     50- $C_s$ is the concentration of monovalent salt(1/|Ang| - converted from mol/L). 
     51 
     52- $\alpha$ is the degree of ionization (the ratio of charged monomers to the total  
     53  number of monomers) 
     54 
     55- $C_a$ is the polymer molar concentration (1/|Ang| - converted from mol/L) 
     56 
     57- $background$ is the incoherent background. 
    4858 
    4959For 2D data the scattering intensity is calculated in the same way as 1D, 
     
    6272that in that implementation, while both the polymer concentration and salt 
    6373concentration were converted from experimental units of mol/L to more 
    64 dimensionally useful units of 1/|Ang|^3, only the converted version of the 
     74dimensionally useful units of 1/|Ang^3|, only the converted version of the 
    6575polymer concentration was actually being used in the calculation while the 
    66 unconverted salt concentration (still in apparent units of mol/L) was being used.  This 
    67 was carried through to sasmodels as used for sasview 4.1(though the line of code converting 
    68 the salt concentration to the new units was removed somewhere along the line). 
    69 Simple dimensional analysis of the calculation shows that the 
    70 converted salt concentration should be used, which the original code suggests 
    71 was the intention, so this has now been corrected (for sasview 4.2). Once better 
    72 validation has been performed this note will be removed. 
     76unconverted salt concentration (still in apparent units of mol/L) was being  
     77used.  This was carried through to Sasmodels as used for SasView 4.1 (though  
     78the line of code converting the salt concentration to the new units was removed  
     79somewhere along the line). Simple dimensional analysis of the calculation shows  
     80that the converted salt concentration should be used, which the original code  
     81suggests was the intention, so this has now been corrected (for SasView 4.2).  
     82Once better validation has been performed this note will be removed. 
    7383 
    7484References 
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