QUANTUM MONTE-CARLO STUDY OF AN EXTENDED HUBBARD-MODEL ON A 2-LEG LADDER

An extended Hubbard model on a two-leg ladder is numerically studied b y 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 ch emical potential show two cliff-like regions and a large plateau regio n. Results on the charge susceptibility suggest it diverges in these c liff-like regions. These observations might imply a signal to the phas e separation, which should be related to the effective attractive inte ractions along chains.