We discuss the exact bond-ordered ground states of the one-dimensional half-filled generalized Hubbard model including three- and four-body terms, by decomposing the Hamiltonian into positive semidefinite parts. The obtained exact ground states are interpreted as Néel ordered states on the bond-located electrons. We determine parameter regions of the exact ground states. We also calculate elementary excitation energies as variational approach based on the matrix-product formalism.

• Received 12 March 2005

DOI:https://doi.org/10.1103/PhysRevB.72.115121