Hopping polaronic motion in high-T-c superconductors

The motion of small polarons is studied as a function of temperature in the context of a molecular crystal model in which the discreteness of the latt ice is accounted for. The polaron bandwidth and the site jump hopping proba bility have been calculated vs. temperature and dimensionality. The crossov er temperature T-d* between band-like and hopping motion is reduced in low- dimensional systems due to the enhanced importance of the off-diagonal scat tering processes. We discuss the relevance of the model to high-T-c superco nductors in which polaronic features in the transport properties have been pointed out [M. Zoli, Phys. Rev. B 53 (1996) 9074; M. Zoli, Phys. Rev. B 56 (1997) 111]. (C) 1999 Elsevier Science B.V. All rights reserved.