2-HOLE D-WAVE BINDING IN THE PHYSICAL REGION OF THE T-J MODEL - A GREENS-FUNCTION MONTE-CARLO STUDY

We investigate numerically the ground state of two holes with dx2-y2 symmetry in the two-dimensional t-J model, on lattices of significantly larger sizes than the ones studied so far. The Green's-function Monte Carlo method, in conjunction with suitable initial states and guidance functions, is used to estimate the ground-state energy of one and two holes, as well as to compute the two-hole distribution function. Our results show a significant decrease of the two-hole binding energy as the size of the lattice is increased from 4 X 4. A critical value J(c) approximately 0.27t is found such that d-wave hole binding no longer occurs for J < J(c).