Relationship between Kubo-transformed and classical correlation functions

A general relation between a Kubo-transformed correlation function of nonlinear operators and its classical analog is derived. The usefulness of this relation lies in the fact that quantum transport properties of systems with a large number of degrees of freedom can be evaluated using only classical simulation data as input. Numerical results of the quantum correction approach employing this relation for nonlinear correlation functions are shown to be in excellent agreement with the exact quantum results.