Radial distribution function

Summary

Let $g(r)$ be the radial distribution function of a homogeneous and isotropic fluid. It compares the density of particles at distance $r$ from a given particle with the average density. It is the basic quantity that describes the local structure of liquids and gases. It can be measured by X-ray or neutron scattering, through its Fourier transform, the structure factor. For pair potentials, the energy, the pressure and the compressibility of the fluid can all be written as integrals of $g$.