Low-energy states with different symmetries in the t-J model with two holes on a 32-site lattice -: art. no. 205101

We study the low-energy states of the t-J model with two holes on a 32-site lattice with periodic boundary conditions. In contrary to common belief, we find that the state with d(x)(2)-y(2) symmetry is not always the ground state in the realistic parameter range 0.2less than or equal toJ/tless than or equal to0.4. There exist low-lying finite-momentum p states whose energies are lower than the d(x)(2)-y(2) state when J/t is small enough. We compare various properties of these low-energy states at J/t=0.3 where they are almost degenerate and find that those properties associated with the holes (such as the hole-hole correlation and the electron momentum distribution function) are very different between the d(x)(2)-y(2) and p states, while their spin properties are very similar. Finally, we demonstrate that by adding "realistic" terms to the t-J model Hamiltonian, we can easily destroy the d(x)(2)-y(2) ground state. This casts doubt on the robustness of the d(x)(2)-y(2) state as the ground state in a microscopic model for the high-temperature superconductors.