New physical insight into the correspondence between path integral concepts
and the Schr\"odinger formulation is gained by the analysis of the effective
classical potential, that is defined within the Feynman path integral
formulation of statistical mechanics. This potential is related to the
quasi-static response of the equilibrium system to an external force. These
findings allow for a comprehensive formulation of dynamical approximations
based on this potential.Comment: 10 pages, 4 figure