  A procedure based on the recently developed ``adaptive'' time-dependent
density-matrix-renormalization-group (DMRG) technique is presented to calculate
the zero temperature conductance of nanostructures, such as a quantum dots
(QD's) or molecular conductors, when represented by a small number of active
levels. The leads are modeled using non-interacting tight-binding Hamiltonians.
The ground state at time zero is calculated at zero bias. Then, a small bias is
applied between the two leads, the wave-function is DMRG evolved in time, and
currents are measured as a function of time. Typically, the current is expected
to present periodicities over long times, involving intermediate well-defined
plateaus that resemble steady states. The conductance can be obtained from
those steady-state-like currents. To test this approach, several cases of
interacting and non-interacting systems have been studied. Our results show
excellent agreement with exact results in the non-interacting case. More
importantly, the technique also reproduces quantitatively well-established
results for the conductance and local density-of-states in both the cases of
one and two coupled interacting QD's. The technique also works at finite bias
voltages, and it can be extended to include interactions in the leads.
