2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/28629An appropriate extension of the effective potential theory is presented that permits the approximate calculation of the dynamical correlation functions for quantum systems. These are obtained by evaluating the generating functionals of the Mori products of quantities related to the relaxation functions in the (PQSCHA) pure self consistent harmonic approximation.Proceedings of the Conference "Path-Integral from peV to TeV. 50 years from Feynman's paper." Florence August 1998. Latex version, 4 pagesStatistical Mechanicstext