2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/145579We derive an effective spin Hamiltonian for the one-dimensional half-filled tetramerized ionic-Hubbard model in the limit of strong on-site repulsion. We show that the effective Hamiltonian which describes the low-energy spin sector of the model is a spin S=1/2 Heisenberg Hamiltonian with alternating nearest-neighbour exchange.8 pages, no figures or tablesStrongly Correlated Electronstext