Radial distribution function: Difference between revisions

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short desc
m Blue if center measure is within dv.
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If a given particle is taken to be at the origin O, and if <math>\rho =N/V</math> is the average number density of particles, then the local time-averaged density at a distance <math>r</math> from O is <math>\rho g(r)</math>. This simplified definition holds for a [[homogeneous]] and [[isotropic]] system. A more general case will be considered below.
 
In simplest terms it is a measure of the probability of finding a particle at a distance of <math>r</math> away from a given reference particle, relative to that for an ideal gas. The general algorithm involves determining how many particles are within a distance of <math>r</math> and <math>r+dr</math> away from a particle. This general theme is depicted to the right, where the red particle is our reference particle, and blue particles are those whichwhose centers are within the circular shell, dotted in orange.
 
The radial distribution function is usually determined by calculating the distance between all particle pairs and binning them into a histogram. The histogram is then normalized with respect to an ideal gas, where particle histograms are completely uncorrelated. For three dimensions, this normalization is the number density of the system <math>( \rho )</math> multiplied by the volume of the spherical shell, which symbolically can be expressed as <math>\rho \, 4\pi r^2 dr</math>.