Abstract
The and Heisenberg models are truncated expansions of a canonically transformed Hubbard model coinciding with it at . We show that a modified canonical transformation applied to the Hubbard model leads to alternative models of similar form but whose convergence properties with respect to the expansion are more favorable, resulting in a good description of the half-filled ground state even at . We investigate the transformed Hamiltonian and observables for metallic and insulating variational wave functions.
- Received 18 December 2007
DOI:https://doi.org/10.1103/PhysRevB.78.033110
©2008 American Physical Society