2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/107074We review basic theoretical concepts and developments regarding the local and itinerant properties of off-center vibronic polarons in crystals. These include the electron self-trapping and the local rotation of the species on a square planar lattice. Phase transitions within the gas of vibronic small polarons are also discussed.14 pages pdf formatSuperconductivitytext