Ground-state properties of the two-dimensional t-J model

The two-dimensional t-J model in the ground state is investigated by the power Lanczos method. The pairing-pairing correlation function for d(x2-y2)-wave symmetry is enhanced in the realistic parameter regime for high-T-c superconductors. The charge susceptibility chi(c) shows divergent behavior as chi(c) proportional to delta(-1) near half filling for the doping concentration delta, indicating that the value of the dynamical exponent z is four under the assumption of hyperscaling. The peak height of the spin structure factor S-max(Q) also behaves as S-max(Q)proportional to delta(-1) near half filling, which leads to the divergence of the antiferromagnetic correlation length xi(m) as xi(m) proportional to delta(-1/2). The boundary of phase separation is estimated on the basis of the Maxwell construction. Numerical results are compared with experimental features observed in high-T-c cuprates.