  In this work we theoretically study properties of electric current driven by
a temperature gradient through a quantum dot/molecule coupled to the source and
drain charge reservoirs. We analyze the effect of Coulomb interactions between
electrons on the dot/molecule and of thermal environment on the thermocurrent.
The environment is simulated by two thermal baths associated with the
reservoirs and kept at different temperatures. The scattering matrix formalism
is employed to compute electron transmission through the system. This approach
is further developed and combined with nonequilibrium Green's functions
formalism, so that scattering probabilities are expressed in terms of relevant
energies including the thermal energy, strengths of coupling between the
dot/molecule and charge reservoirs and characteristic energies of
electron-phonon interactions. It is shown that one may bring the considered
system into regime favorable for heat-to-electric energy conversion by varying
the applied bias and gate voltages.
