  An extended Hubbard model on a two-leg ladder is numerically studied by means
of the quantum Monte Carlo techniques. The model we study has the
nearest-neighbor interactions which are repulsive along chains and attractive
for rungs. The plots of the doping parameter versus the chemical potential show
two cliff-like regions and a large plateau region. Results on the charge
susceptibility suggest it diverges in these cliff-like regions. These
observations might imply a signal to the phase separation, which should be
related to the effective attractive interactions along chains.
