First-principles study on the origin of large thermopower in hole-doped LaRhO(3) and CuRhO(2).

Based on first-principles calculations, we study the origin of the large thermopower in Ni-doped LaRhO(3) and Mg-doped CuRhO(2). We calculate the band structure and construct the maximally localized Wannier functions from which a tight binding Hamiltonian is obtained. The Seebeck coefficient is calculated within the Boltzmann's equation approach using this effective Hamiltonian. For LaRhO(3), we find that the Seebeck coefficient remains nearly constant within a large hole concentration range, which is consistent with the experimental observation. For CuRhO(2), the overall temperature dependence of the calculated Seebeck coefficient is in excellent agreement with the experiment. The origin of the large thermopower is discussed.