ELECTRONIC-STRUCTURE AND FINAL-STATE EFFECTS IN ND2CUO4, LA2CUO4, ANDCA2CUO3 COMPOUNDS BY MULTICHANNEL MULTIPLE-SCATTERING THEORY AT THE COPPER K-EDGE

We present a theoretical analysis, based on the zeroth-order approxima tion of the multichannel multiple-scattering theory, of the x-ray-abso rption spectra of Nd2CuO4, La2CuO4, and Ca2CuO3 compounds at the coppe r K edge. Single-channel theoretical calculations have been made using atomic clusters large enough to be sure that all one-electron feature s have been correctly described. On this basis the presence of both 3d (9) and <3d(10)(L)under bar> configurations in the ground state has be en found essential to obtain good agreement between experimental data and theoretical calculations in the case of Nd2CuO4 and Ca2CuO3. Conve rsely, the best agreemnt with the La2CuO4 data has been obtained by ta king into account only the <3d(10)(L)under bar> configuration in the f inal state. We briefly comment on this finding.