  We study the dynamical thermoelectric transport in metals subjected to the
electron-impurity and the electron-phonon interactions using the memory
function formalism. We introduce a generalized Drude form for the Seebeck
coefficient in terms of thermoelectric memory function and calculate the later
in various temperature and frequency limits. In the zero frequency and high
temperature limit, we find that our results are consistent with the
experimental findings and with the traditional Boltzmann equation approach. In
the low temperature limit, we find that the Seebeck coefficient is quadratic in
temperature. In the finite frequency regime, we report new results: In the
electron-phonon interaction case, we find that the Seebeck coefficient shows
frequency independent behavior both in the high frequency regime ($\omega \gg
\omega_{D}$, where $\omega_{D}$ is the Debye frequency) and in the low
frequency regime ($\omega \ll \omega_{D}$), whereas in the intermediate
frequencies, it is a monotonically increasing function of frequency. In the
case of the electron-impurity interaction, first it decays and then after
passing through a minimum it increases with the increase in frequency and
saturates at high frequencies.
