In this talk, we address the inability of conventional NEMD methods to study the response of a liquid subjected to experimentally accessible fields. For this purpose, we use the transient time correlation function (TTCF) formalism. The TTCF formalism is essentially a nonlinear generalization of the Green-Kubo relations. We show how the TTCF approach can be applied to determine the conductivity of a fluid confined in a nanopore and subjected to a realistic (experimentally accessible) field . Our results provide a full picture of the dependence of conductivity on the applied field and on the effective diameter of the nanopore.
 C. Desgranges and J. Delhommelle, Phys. Rev. E 77, 027701 (2008)