Polaron mobility obtained by a variational approach for lattice Fröhlich models

Abstract

Charge carrier mobility for a class of lattice models with long-range electron–phonon interaction was investigated. The approach for mobility calculation is based on a suitably chosen unitary transformation of the model Hamiltonian which transforms it into the form where the remaining interaction part can be treated as a perturbation. Relevant spectral functions were then obtained using Matsubara Green’s functions technique and charge carrier mobility was evaluated using Kubo’s linear response formula. Numerical results were presented for a wide range of electron–phonon interaction strengths and temperatures in the case of one-dimensional version of the model. The results indicate that the mobility decreases with increasing temperature for all electron–phonon interaction strengths in the investigated range, while longer interaction range leads to more mobile carriers.