DYNAMICS OF 2 HOLES IN THE T-J MODEL

Ground state properties of two holes in the antiferromagnetic state in a square lattice are studied by using the t-J model and a variational method where the Hilbert space is restricted. It is shown that two holes are bound to each other and the ground state has d-symmetry for J/\t\ greater than or similar to 0.18 with the momentum K=(0, 0). The binding energy of two holes is -0.7 approximately -0.5 x J/\t\ and the average distance between two holes is 1.6 approximately 1.8 x a, where a is the lattice constant, for realistic parameter values. Static correlation function S(zz)(Q) shows a broad peak around Q=(pi/2, pi/2) which originates from the motion of holes. By making use of the results for one and two holes, an effective Hamiltonian for the quasi-particles is proposed.