Substantiation of the Method of Density Functional in Classical and Quantum Statistical Mechanics

Abstract

The relationship between a description of a multicomponent mixture based on the entropy functional with the terms quadratic in the density gradients of components and in the temperature on the one hand, and a description within the framework of classical and quantum statistical mechanics on the other hand, is investigated. Explicit expressions for the entropy functional are written in the context of classical and quantum theories. A quadratic approximation is then calculated for the case of small perturbations of a uniform state. The terms quadratic in the gradients are separated in this approximation. This allows ab initio calculations of the corresponding phenomenological coefficients to be done.