Two-holed-wave binding in the physical region of thet-Jmodel: A Green’s-function Monte Carlo study

We investigate numerically the ground state of two holes with ${\mathit{d}}_{\mathit{x}}^2$-${\mathit{y}}^2$ 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 4×4. A critical value ${\mathit{J}}_{\mathit{c}}$∼0.27t is found such that d-wave hole binding no longer occurs for J<${\mathit{J}}_{\mathit{c}}$.