Abstract
We describe a unitary transformation which eliminates terms coupling states with differing numbers of doubly occupied sites from the Hamiltonian of the Hubbard model. The matrix for the transformation, and the transformed Hamiltonian, , are generated by an iterative procedure which results in an expansion in powers of the hopping integral divided by the on-site energy . For a half-filled band and in the space with no doubly occupied sites, is equivalent to a spin Hamiltonian. We discuss the implications of our results for on theories of high-temperature superconductivity.
- Received 8 January 1988
DOI:https://doi.org/10.1103/PhysRevB.37.9753
©1988 American Physical Society