Characteristics of the electron structure of high-temperature superconducting yttrium ceramic compounds

In an attempt to understand the nature of the high-temperature superconductivity of Y123 ceramics, quantum-chemical calculations are carried out for the Cu3O12 cluster modeling YBa2Cu3O7, the Cu3O10 cluster modeling YBa2Cu3O6, and also CuZn2O12 and CuZn2O10 clusters corresponding to the substitution of Cu(2) atoms in Cu-O planes. The clusters are calculated in terms of the Madelung potential using a specially developed computer program. The electron density distributions for the clusters investigated are presented, and possible mechanisms of high-temperature conductivity are discussed in the light of the results obtained.