Charge Transfers and Band Dispersions in Magnetic Nd2-x Ce x CuO4

The electronic structure of Ce-doped Nd2-x Ce (x) CuO4 (NCCO) is investigated through ab-initio density functional calculations for supercells. The effective electron doping, h, i.e., the additional electronic charge per Cu atom due to Ce doping, is found to be significantly smaller than x. The explanation of this result is to be found in the hybridization of the CuO band with the Nd-f bands. This hybridization makes the Fermi surface break to occur at a larger k-vector than what is expected from the unhybridized band. The true band dispersion of the CuO band near E (F) is different from what is seen in ARPES, which partly can be understood from calculations of relaxation energies in photoemission.