Chemical bond and electronic structure in \\123 and 124 superconductors

Abstract

In order to correlate the structural units and unit cells in the Y123 and Y124 systems, we have carried out ASED-MO calculation with charged model clusters with and without point charges. The charged model clusters for the Y123 system were CuO 4 −6, CuO 5 −8, CuO 4 −6 and Cu 3O 12 −18 without point charges and CuO 4H 4 −2, CuO 4−6, CuO 5−8, Cu 2O 6−8 and Cu 4O 14−20 without point charges and CuO 4H 4−2, CuO 5H 4−4, Cu 2O 6 H 4−4 and Cu 4O 14H 12−8 with point charges. We found that the charged model clusters relating to the structural units can not describe the real properties of the Y123 and Y124 superconductors, so we need to use the charge model clusters relating to the entire unit cell. The oxidation state of Cu in the layer of Y123 system is higher than the oxidation state of Cu in the layer of Y124 system.