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