Local lattice structures,random spatial processes and molecular correlations in liquids

Structural and molecular correlations in a liquid are treated by a set of Fokker—Planck type equations for the spatial evolution of the probability density P(sr) of fluctuating local structure parameters s. The equations are generalizations of the “structural diffusion” equations. including in addition to second order terms also first order terms in the derivatives of P(sr) with respect to the components of s. A proper choice of the coefficients in these terms leads to an apparent shift of the peaks of the local quasi-lattice and to an improved radial distribution function g(r)- Comparison with g(r) data for argon was made for several different lattices. showing a best fit of r²g(r)-1] with the bcc quasi-lattice.