Article révisé par les pairs
| Résumé : | A general formula for the time dependent electric current arising from a constant electric field is derived along the line of ideas of Kubo's theory. This formula connects the time dependence of the current to the singularities of the resolvant of Liouville's operator of a classical system. It permits to make direct contact with the general theory of approach to equilibrium developed by Prigogine and his coworkers. It constitutes a framework for a diagram expansion of transport coefficients. A proof of the existence of a stationary state of its stability (to first order in the field) are given. It is rigorously shown that, whereas the approach to the stationary state is in general governed by complicated non-markoffian equations, the stationary state itself (and thus the calculation of transport coefficients) is always determined by an asymptotic cross section. This implies that transport coefficients can always be calculated from a markoffian Boltzmann-like equation even in situations in which that equation does not describe properly the approach to the stationary state. © 1961. |
