An analytical method of computation of radial distribution functions at large distances for liquids and amorphous substances

An analytical method is proposed to obtain quantitatively the radial distribution function (RDF) at large distances for liquids and amorphous materials from the structure factor [S(q)] data in the region of its main peak only. The RDF's obtained prove to be unaffected by the random spread of the experimental points at the tail of S(q). The method is illustrated for a number of simple liquids and for liquid and amorphous solid water. The application of the method to the S(q) extrapolation to the low-q region and the problem of the experimental determination of the direct correlation function are discussed.