Modified algebraic Bethe ansatz for XXZ chain on the segment - II -   general cases
  The spectral problem of the Heisenberg XXZ spin-$\frac{1}{2}$ chain on the segment is investigated within a modified algebraic Bethe ansatz framework. We consider in this work the most general boundaries allowed by integrability. The eigenvalues and the eigenvectors are obtained. They are characterised by a set of Bethe roots with cardinality equal to $N$, the length of the chain, and which satisfies a set of Bethe equations with an additional term. 
Samuel Belliard and Rodrigo A. Pimenta
math-ph cond-mat.stat-mech hep-th math.MP nlin.SI