  Resonant tunneling through quantum dot under a finite bias voltage at zero
temperature is investigated by using the adaptive time-dependent density matrix
renormalization group(TdDMRG) method. Quantum dot is modeled by the Anderson
Hamiltonian with the 1-D nearest-neighbor tight-binding leads. Initially the
ground state wave function is calculated with the usual DMRG method. Then the
time evolution of the wave function due to the slowly changing bias voltage
between the two leads is calculated by using the TdDMRG technique. Even though
the system size is finite, the expectation values of current operator show
steady-like behavior for a finite time interval, in which the system is
expected to resemble the real nonequilibrium steady state of the infinitely
long system. We show that from the time intervals one can obtain quantitatively
correct results for differential conductance in a wide range of bias voltage.
Finally we observe an anomalous behavior in the expectation value of the double
occupation operator at the dot $<n_{\uparrow} n_{\downarrow}>$ as a function of
bias voltage.
