You need to look at the equations for the radial distribution function.
The key is this "scaling factor" which is in fact the density. From the
old ptraj source:
/*
* output Allen & Tildesley style histogram, i.e.
*
* histogram[bin]
* ----------------------------------------------------------
* (4/3)*pi*density*[(R+delR)**3 - R**3] * frames * molecules
*/
Depending on how you specify the density (it defaults to a particular
value), you will get the same result and the density choice differs
depending on your reference (the first mask).
If you want the behavior to be as you suggest, you are going to need a
means to either use the system volume or re-write the code to do the
normalization in the way you think it should be done.
-tec3
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Received on Fri Feb 01 2013 - 11:00:02 PST
