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

Abstract

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( s r) 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( s r) 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 r 2[ g( r)-1] with the bcc quasi-lattice.