THE PECULIARITIES OF THE ELECTRONIC-STRUCTURE OF LA2CUO4 AND YBA2CU3O7-DELTA COMPOUNDS

The electronic structure of La1-xMexCuO4 and YBa2Cu3O7-delta compounds are studied theoretically. The band structure of La2CuO4 crystal is c alculated by relativistic linear muffin-tin orbitals (LMTO) method. Th e X-ray emission spectra of oxygen, copper and lanthanum have been cal culated. There exists a good agreement between the theoretical and exp erimental data. In the present calculation particular attention was pa id to the correct description of La and Ba electron states, that is to the ''generating'' 4f-states of the atom. Our results differ from tho se obtained previously. Much attention is paid to the role of La and B a atoms in the formation of the energy spectrum of the crystal. To exp lain the La and Ba M and N X-ray absorption and emission experimental spectra the electronic structure of ground and several excited states of [LaBaCu4O22] and [YBaCu8On] clusters has been calculated by X(alpha )-scattering wave (SW) method. The obtained densities of the electron states are in a good agreement with the experimental spectra. Our inve stigation reveals the essential role of La and Ba 4f-states in the for mation of the energy spectrum near the Fermi level.