Inelastic effects in molecular junction transport: scattering and self-consistent calculations for the Seebeck coefficient

The influence of molecular vibration on the Seebeck coefficient is studied within a simple model. Results of a scattering theory approach are compared with those of a full self-consistent non-equilibrium Green's function scheme. We show, for a reasonable choice of parameters, that inelastic effects have a non-negligible influence on the resulting Seebeck coefficient for the junction. We note that the scattering theory approach may fail both quantitatively and qualitatively. The results of calculations with reasonable parameters are in good agreement with recent measurements [Science 315, 1568 (2007)].