  Another way to evaluate the spectral-correlation properties of thermal fields
of solids is suggested. Such a method takes into account detailed structure of
the interface transition layer separating one bulk region from those of the
vacuum region. The principal element here is the surface linear response
function of an arbitrary inhomogeneous electron subsystem of solids. Along with
straightforward using the known response functions, for example in a
hydrodynamic approach, the suggested method allows calculating the response
functions self-consistently based on the time dependent density functional
theory. The self-consistent calculation of the linear response function
followed by an application of the fluctuation-dissipation theorem yield in the
spectral power densities of the fluctuating charge and current correlation
functions. The final step of this sequence of actions aiming in obtaining the
spectral-correlation properties of thermal fields of solids at any distances.
