Carrier-density effects in many-polaron systems

Abstract

Many-polaron systems with finite charge-carrier density are often encounteredexperimentally. However, until recently, no satisfactory theoretical description of thesesystems has been available even in the framework of simple models such as theone-dimensional spinless Holstein model considered here. In this work, previous resultsobtained using numerical as well as analytical approaches are reviewed from a unifiedperspective, focusing on spectral properties which reveal the nature of the quasiparticles inthe system. In the adiabatic regime and for intermediate electron–phonon coupling, acarrier-density driven crossover from a polaronic to a rather metallic system takes place.Further insight into the effects due to changes in density is gained by calculating thephonon spectral function, and the fermion–fermion and fermion–lattice correlationfunctions. Finally, we provide strong evidence against the possibility of phase separation.