Response Function Theory for Many-Body Systems away-from Equilibrium: Conditions of Ultrafast-Time and Ultrasmall-Space Experimental Resolution

摘要

A Response Function Theory and Scattering Theory applicable to the study ofphysical properties of systems driven arbitrarily away from equilibrium,specialized for dealing with ultrafast processes and in conditions of spaceresolution (including nanometric scale), are presented. The derivation is donein the framework of a Gibbs-style Nonequilibrium Statistical EnsembleFormalism. It is shown the connection of the observable properties with timeand space-dependent correlation functions out of equilibrium. A generalizedfluctuation-dissipation theorem, which relates these correlation functions withgeneralized susceptibilities is derived. It is also presented the method,useful for calculations, of nonequilibrium-thermodynamic Green functions. Acouple of illustration with application of the formalism, consisting of thestudy of optical responses in ultrafast laser spectroscopy and Raman Scatteringof electrons in III-N semiconductors (of "blue diodes") driven away fromequilibrium by action of electric fields of moderate to high intensities, aredescribed.