Electronic structure and chemical bonding in Ba-Cu-O layer systems

The cluster method of discrete variation was used to study compounds containing chains of plane-coordinated copper ions separating oxygen-copper planes. We also examined real YBa₂Cu₃O₇ and hypothetical MBa₃Cu₄O₉ systems (M is a tetravalent metal ion). A study was carried out on the transformation of the valence band and structure of the molecular orbitals in the Fermi level in going from YBa₂Cu₃O₇ to MBa₃Cu₄O₉. The chemical bonding was analyzed and the role of the interchain interaction in the bonding of the copper and oxygen atoms in different crystallographic positions was determined.Institute of Chemistry, Urals Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 5, pp. 17–20, September–October, 1989.