INTEGRABILITY OF OPEN SPIN CHAINS WITH QUANTUM ALGEBRA SYMMETRY

We construct an open quantum spin chain from the "twisted" A2(2) R matrix in the fundamental representation which has the quantum algebra symmetry U(q)[su(2)]. This anisotropic spin-1 chain is different from the U(q)[su(2)]-invariant chain constructed from the "untwisted" A1(1) spin-1 R matrix (namely, the spin-1 XXZ chain of Fateev-Zamolodchikov with boundary terms) but, nevertheless, is also completely integrable. We discuss the general case of an R matrix of the type g(k), where k is-an-element-of {1, 2, 3}, and g is any simple Lie algebra.