ABSTRACT
The linear response theory which is expounded in the present chapter permits one to determine the response function of classical and quantum Coulomb systems with strong interparticle interactions to a longitudinal electrical field, an electromagnetic field and thermal disturbances. Let us explain the notions of mechanical disturbances used in LRT. The mechanical disturbances of a system are the result of the action of external fields, the system's Hamiltonian being a sum of unperturbed Hamiltonian and a Hamiltonian of the interaction of a system with an external field. The microscopic expressions are obtained in §§ 1,2 of the present chapter using the concept of a mechanical disturbance along with examination of the properties of two-component Coulomb system response functions which are of physical interest. The LRT for mechanical disturbances the results of which are used below is developed in [5]. Flows of heat, mass, momentum and charge presented in the conservation equations of a charged condensed high-temperature medium do not contain external fields because
the longitudinal electrical field in the equations of electric current, heat and mass fluxes is, generally speaking, a mean field in the medium. Because of that, the approach is stated in §3 to investigations of phenomenological kinetic coefficients local values corresponding to thermal disturbances — mean electric field, gradients of temperature and chemical potentials medium components, medium mass velocity. This approach is based on the representation of conservation equations as generalized Langevin equations [6 - 8]. As this takes place, in contrast to [9], the irreducibility of some phenomenological kinetic coefficients to the corresponding Kubo coefficients (compare with [10]) is demonstrated. The existence of other approaches to the description of thermal disturbances within condensed media [11 - 14] in addition to the one developed in the present chapter should be mentioned (see also § 4).
