Electron-phonon interaction on bundled structures: Static and transport properties - art. no. 014303

We study the small-polaron problem of a single electron interacting with th e lattice for the Holstein model in the adiabatic limit on a comb lattice h en the electron-phonon interaction acts only on the base sites. The ground state properties can be easily deduced from the ones of a linear chain with a appropriate rescaling of the coupling constant. On the other hand, the d ynamical properties, that involve the complete spectrum of the system, pres ent an "exotic" behavior. In the weak coupling limit the Drude weight (zero -frequency-conductivity) is enhanced with respect to its free-case value, c ontrary to the linear chain case, where for every finite value one has supp ression of the Drude peak. More interestingly, the loss of coherent electro n motion and the polaronic localization of the carrier occurs for different coupling values. Thus for intermediate coupling, a different phase appears with large kinetic energy and no coherent motion.