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

DOI:https://doi.org/10.1103/PhysRevB.55.1435