We present a simple method for the construction of exact ground states of generalized Hubbard models in arbitrary dimensions. This method is used to derive rigorous criteria for the stability of various ground state types, like the $\eta$-pairing state, or Néel and ferromagnetic states. Although the approach presented here is much simpler than the ones commonly used, it yields better bounds for the region of stability.

• Received 21 March 1995

DOI:https://doi.org/10.1103/PhysRevLett.75.4298