QUANTUM SYMMETRY OF HUBBARD-MODEL UNRAVELED

Superconducting quantum symmetries in extended one-band one-dimensiona l Hubbard models are shown to originate from the classical (pseudo-)sp in symmetry of a new class of models; the standard Hubbard model is a special case. The quantum symmetric models provide extra parameters bu t are restricted to one dimension. All models discussed are related by generalized Lang-Firsov transformations, some have symmetries away fr om half filling. (C) 1997 Elsevier Science B.V.