2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/18225We present a single-orbital double-exchange model, coupled with cooperative phonons (the so called breathing-modes of the oxygen octahedra in manganites). The model is studied with Monte Carlo simulations. For a finite range of doping and coupling constants, a first-order Metal-Insulator phase transition is found, that coincides with the Paramagnetic-Ferromagnetic phase transition. The insulating state is due to the self-trapping of every carrier within an oxygen octahedron distortion.4 pages, 5 figures, ReVTeX macro, accepted for publication in PRLMaterials ScienceStatistical Mechanicstext