Generalization of Lieb-Wu wave function inspired by one-dimensional ionic Hubbard model

With the ionic Hubbard model (IHM) in mind, we construct a non-trivial generalization of the Bethe ansatz (BA) wave function which naturally generalizes the Lieb-Wu wave function with an ionic parameter Delta, and reduces to Lieb-Wu solution in the limit Delta -> 0. The resulting two-particle scattering matrix satisfies the Yang-Baxter equation. To the extent that the unit cells with more than two electrons (Choy-Haldane issue) are avoided on average, our wave function represents an effective solution for the one-dimensional IHM. The Choy-Haldane issue limits the validity of our solution to low-filling and large U greater than or similar to 4. This regime is attainable in cold atom realizations of the IHM. For this regime, we numerically solve the generalized Bethe equations and compute the ground state energy in the thermodynamic limit. (C) 2020 Elsevier Inc. All rights reserved.