Changeset 20c856a in sasmodels for sasmodels/models/rpa.c

Timestamp:

Mar 7, 2017 1:19:23 AM (8 years ago)

Author:

butler

Branches:

master, core_shell_microgels, costrafo411, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

9ae85f0, 3a45c2c

Parents:

f4b36fa

Message:

Final rpa model corrections (correct scale and units) and verified with
one of original authors on paper. Fixes #593.

while documentation was updated minimally to be usable it could use more
thorough work as can many which is the subject of other tickets. Also
annoying is that the example plot is useless. It is however
autogenerated from "default parameters" which is not helpful in this
particular case. Will submit new ticket for that.

File:

• sasmodels/models/rpa.c (modified) (2 diffs)

sasmodels/models/rpa.c

@@ -309 +309 @@
 
   //calculate contrast where L[i] is the scattering length of i and D is the matrix
-  //need to verify why the sqrt of Nav rather than just Nav (assuming v is molar volume)
+  //Note that should multiply by Nav to get units of SLD which will become
+  // Nav*2 in the next line (SLD^2) but then normalization in that line would
+  //need to divide by Nav leaving only Nav or sqrt(Nav) before squaring. 
   Nav=6.022045e+23;
   Lad=(L[0]/v[0]-L[3]/v[3])*sqrt(Nav);
@@ -317 +319 @@
   Intg=Lad*Lad*S11+Lbd*Lbd*S22+Lcd*Lcd*S33+2.0*Lad*Lbd*S12+2.0*Lbd*Lcd*S23+2.0*Lad*Lcd*S13;
 
-  //rescale for units of Lij^2 (in 10e-12 m^2 to m^2 ?)
-  Intg *= 1.0e-24;    
+  //rescale for units of Lij^2 (fm^2 to cm^2)
+  Intg *= 1.0e-26;    
 
   return Intg;