Talk:Radial distribution function

In the near future I will be adding the formal derivation of g(r) in the article... 14-02-2007 - Joris Kuipers
Nice, I am thinking that maybe some information about/from experiments might be useful. Like Alan Sopers articles. omermar 30/05/07

Eq. 13

The line below equation 13 reads: "In fact, equation 13 gives us the number of molecules between r and r + d r about a central molecule." However, it looks to me that equation 13 gives us the total number N of the molecules of the system, .... Lwzhou (talk) 12:22, 6 October 2008 (UTC)lwzhou[reply]

As I understand, the current version of eq. 13 gives the TOTAL number of molecules in the SYSTEM (since it is from zero to infinity).
I suggest the following correction:
1) Make the range of the integral from r1 to r2.
2) Add/modify the text: Eq. 13 gives the number of molecules in the solvation shell of a central molecule, when r1 & r2 are picked at consecutives minimums of the RDF function. For example - for the number of molecules in the first solvation shell, r1=0 & r2 is picked at the second minimum of g(r).
For water, when r1=0 & r2=3.5 Angstroms, then N ~ 4.5 molecules.

omermar --http://www.fh.huji.ac.il/~omerm 07:56, 7 October 2008 (UTC)[reply]

Just a short comment: as far as I understand it in eq. 13 g(r) does not give the number of molecules between r and r+dr. You would still have to multiply it with the particle density and 4Pi r^2. Suggestions 1) and 2) of above are still correct. —Preceding unsigned comment added by 141.24.104.201 (talk) 14:10, 11 November 2008 (UTC)[reply]

Is it true that the integrand times dr gives the the number of molecules between r and r+dr. Is g(r) here in Eq. 13 means the probability finding often a molecule at the distance r from a reference molecule and called pair distribution function, while the integrand in Eq. 13 times dr called radial distribution function? It seems that different sources give different definitions of PDF and RDF. Could someone clarify it?