We present a quantum-kinetic scheme for the calculation of non-equilibrium
transport properties in nanoscale systems. The approach is based on a
Liouville-master equation for a reduced density operator and represents a
generalization of the well-known Boltzmann kinetic equation. The system,
subject to an external electromotive force, is described using periodic
boundary conditions. We demonstrate the feasibility of the approach by applying
it to a double-barrier resonant tunneling structure