[gmx-users] How is the particle density of type B computed in g_rdf ?

[David van der Spoel]

Grace Li wrote:
> Hi Gromacs users:
> 
> As described in the PDF of Gromacs documentation version 3.3.1 (pp 
> 160-161),  with g_rdf we can compute the radial distribution function 
> between particles of type A and B, where A is the reference group.
> I am not clear on how g_rdf computes the volume in the particle density 
> of type B.   The particle density of type B is represented by 
> <ro_B>_local in the documentation, which I understand to be  N/V, where 
> N is the total number of particles of type B, and V is the volume of the 
> entire box.
> Is this the case?
Yes, the number of B particles in a spherical shell. at distance r 
divided by the average number of B particles per volume.
> 
> Any help is appreciated. 
> 
> Thanks,
> 
> Grace
> 
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se
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