Resistivity peculiarities in systems with lattice distortions

We study a molecular lattice Hamiltonian in which polaronic charge carriers interact with nonlinear potentials provided by local atomic fluctuations b etween two equilibrium sites. The path integral formalism is applied to sel ect the class of atomic oscillations which mainly contributes to the partit ion function and the electrical resistivity is computed in a number of repr esentative cases. Nonmetallic resistivity behaviors are found at temperatur es above similar or equal to 100 K. (C) 2001 Elsevier Science B.V. All righ ts reserved.