Exact ground state of the Hubbard model on a double-layer square lattice
Phys. Rev. B 49, 589 – Published 1 January, 1994
DOI: https://doi.org/10.1103/PhysRevB.49.589
Abstract
A group of analytical wave functions is confirmed to be the ground state of a Hubbard model on a double-layer square lattice in the case of half-filling and in the case with one or two doped holes for a range of parameters. The method is based on the variational principle, and no approximations are applied. In the case of half-filling, the ground state is a product of local pairs. In the case of one or two holes, the doped holes are freely moving in the above background. In both cases there exists a long-range order of the evenness and oddness with respect to the layer parity.