Diffusion in multicomponent liquids: A new set of collective velocity correlation functions and diffusion coefficients

Abstract

A new set of time correlation functions for the description of the microscopic collective dynamic behavior in multicomponent liquids is introduced. These functions, the relative mean molecular velocity correlations, are independent of the considered reference frame and the related diffusion coefficients may be defined. The advantages of this kind of description are discussed and relations between the proposed diffusion coefficients and both phenomenological and empirical transport coefficients are derived. Special attention is devoted to the binary liquids.