  Here we present a theoretical analysis of inelastic effects on thermoelectric
properties of molecular-scale junction in both linear and nonlinear response
regimes. Considered device is composed of molecular quantum dot (with discrete
energy levels) asymmetrically connected to metallic electrodes (treated within
the wide-band approximation) via potential barriers, where molecular vibrations
are modeled as dispersionless phonon excitations. Nonperturbative computational
scheme, used in this work, is based on Green's function theory within the
framework of polaron transformation (GFT-PT) which maps the many-body
electron-phonon interaction problem into a one-body multi-channel
single-electron scattering problem. It is shown that all the thermoelectric
characteristics are dominated by quantum transport of virtual polarons due to a
strong electron-phonon coupling.
