  We simulated the 3-band Hubbard model using the Constrained Path Monte Carlo
(CPMC) method in search for a possible superconducting ground state. The CPMC
is a ground state method which is free of the exponential scaling of computing
time with system size. We calculated the binding energy of a pair of holes for
systems up to $6 \times 4$ unit cells. We also studied the pairing correlation
functions versus distance for both the d-wave and extended s-wave channels in
systems up to $6 \times 6$. We found that holes bind for a wide range of
parameters and that the binding increased as the system size is increased.
However, the pairing correlation functions decay quickly with distance.
  For the extended s channel, we found that as the Coulomb interaction $U_d$ on
the Cu sites is increased, the long-range part of the correlation functions is
suppressed and fluctuates around zero. For the $d_{x^2 - y^2}$ channel, we
found that the correlations decay rapidly with distance towards a small
positive value. However, this value becomes smaller as the interaction $U_d$ or
the system size is increased.
