[ase-users] Radial Distributional Function

[Steen Lysgaard]

Hi Amarjit,

the function used in ase/ga/utilities.py resembles the function you mention very much, the only difference is the volume of the hollow sphere used for normalizing. In your function (4 pi r^2 dr) is used which is an approximation for small dr, but dr is not always small (since the user can set rmax and nbins freely), so instead the volume of the hollow sphere is: 4/3 pi (r + 1/2dr)^3 - 4/3 pi (r - 1/2dr)^3, in the code this equation is simplified.

I hope this explains the discrepancy.

Best regards,
Steen


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From: ase-users-bounces at listserv.fysik.dtu.dk <ase-users-bounces at listserv.fysik.dtu.dk> on behalf of A Singh via ase-users <ase-users at listserv.fysik.dtu.dk>
Sent: Saturday, August 10, 2019 6:04:46 PM
To: ase-users at listserv.fysik.dtu.dk
Subject: [ase-users] Radial Distributional Function

Hello all,

I've been using the get_rdf() function from ase/ga/utilities.py and have noticed that the formula for calculating radial distribution is not the same as found in computational chemistry books. The correct formula I believe is:
g(r)=n(r)/*** ** r2*r)
In which g(r) is the RDF, n(r) is the mean number of atoms in a shell of width *r at distance r, * is the mean atom density, *  is the total number of atoms.
It would be great if someone could explain what has been implemented in get_rdf().


Thanks,

Amarjit Singh Gaba

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