We investigate the Hubbard model, and the extended Hubbard model with and without correlated hopping, as an approximation to the average single-site (or local) entanglement of two-electron one-dimensional quantum dot chains with long range interactions. We focus on the effect of the chain length on the approximation accuracy. We also consider the particle-particle spatial entanglement of the three Hubbard models using the technique of Ref.  and compare the accuracy of this approximation to the numerically exact results of the nanostructure system.
Coe, J. P., França, V. V., & D'Amico, I. (2011). Approximation of the entanglement in quantum dot chains using Hubbard models. Journal of Physics: Conference Series, 286(1), . https://doi.org/10.1088/1742-6596/286/1/012048