INTEGRABLE OPEN-BOUNDARY CONDITIONS FOR THE Q-DEFORMED SUPERSYMMETRICU MODEL OF STRONGLY CORRELATED ELECTRONS

A general graded reflection equation algebra is proposed and the corre sponding boundary quantum inverse scattering method is formulated. The formalism is applicable to all boundary lattice systems where an inve rtible R-matrix exists. As an application, the integrable open-boundar y conditions for the q-deformed supersymmetric U model of strongly cor related electrons are investigated. The diagonal boundary K-matrices a re found and a class of integrable boundary terms are determined. The boundary system is solved by means of the coordinate space Bethe ansat z technique and the Bethe ansatz equations are derived. As a sideline, it is shown that all R-matrices associated with a quantum affine supe ralgebra enjoy the crossing-unitarity property. (C) 1998 Elsevier Scie nce B.V.