FINITE-TEMPERATURE 2-STATE SMALL-POLARON DYNAMICS - AVERAGED HAMILTONIAN APPROACH

We study small-polaron self-trapping properties in the two-state molec ular crystal model by employing a finite-temperature variational non-a diabatic approach that is an extension to the semiclassical adiabatic Pekar theory. We find two distinct regions in the space of coupling co nstant versus adiabaticity parameter that are separated by a temperatu re-dependent critical line. In these regions the response of the latti ce to the motion of the particle is quite different. We find condition s that allow for the determination of the character of the motion and the localization transition as a function of the physical parameters o f the system and temperature.