Spin-1/2 XYZ model revisit: General solutions via off-diagonal Bethe ansatz

The spin-1/2 XYZ model with both periodic and anti-periodic boundary conditions is studied via the off-diagonal Bethe ansatz method. The exact spectra of the Hamiltonians and the Bethe ansatz equations are derived by constructing the inhomogeneous T Q relations, which allow us to treat both the even N (the number of lattice sites) and odd N cases simultaneously in a unified approach. (C) 2014 The Authors. Published by Elsevier B.V.