Ab initio MO Studies on the Correlation and Spin Correlation Effects for Copper-Oxygen and Copper-Halogen Bonds in High-Tc Copper Oxide Superconductors

Abstract

The correlation and spin correlation effects for Cu⁺²XCu⁺² (X=F^-1, Cl^-1 and O^-2) were investigated by the ab initio molecular orbital (MO) method. It is found that these effects are particularly strong for Cu⁺²F^-1Cu⁺², while they are rather weak for Cu⁺²O^-2Cu⁺². Implications of the ab initio MO results are discussed in relation to the high-T _c superconductivity for La-Ba-Cu-O and R-Ba-Cu-O (R=Y, etc.). The working hypotheses derived are applied to the molecular design of organic superconductors.