Structure of liquids. Part 7.—Determination of intermolecular potential functions and correlation functions in fluid argon by X-ray diffraction techniques

Abstract

Methods of obtaining the radial distribution function and the direct correlation function for simple liquids from X-ray diffraction data are reviewed. A new theoretical analysis demonstrates that certain of the cluster integrals appearing in the density expansion of the radial distribution function can be evaluated directly from Fourier transforms of appropriate powers of the X-ray scattering function. These results are used to develop expressions which permit determination of the intermolecular potential function from moderately dense fluids using essentially only X-ray diffraction data. Non-additivity effects may also be treated. Experimental data available are inadequate for conclusive determination of the potential function; however, experimental results from one state of argon give plausible values for the lowest-order cluster integral.