  Thermoelectric transport in strongly spin-orbit coupled two-dimensional
Rashba system is studied using the exact solution of the linearized Boltzmann
equation. Some unusual transport behaviors are revealed. We show that the
electrical conductivity takes a Drude form when the Fermi energy $E_{F}$ is
above the band crossing point, but a non-Drude form which is a quadratic
function of $E_{F}$ when $E_{F}$ lies below the band crossing point. The Mott
relation breaks down when $E_{F}$ lies in the vicinity of the band crossing
point. It is shown that the thermopower and thermoelectric figure of merit are
strongly enhanced when $E_{F}$ downs below the band crossing point. This
enhancement is attributed to not only the one-dimensional-like density of state
but also the unconventional intraband elastic scattering below the band
crossing point. The differences between these results and those obtained by the
relaxation time approximation are discussed in detail.
