WHMO calculations on CuO clusters of YBa2Cu3O7- x: Correlation between T c, structure, oxygen stoichiometry and highest occupied molecular orbital energy

Abstract

WHMO calculations of reasonably big CuO clusters, namely, Cu 12O -42 33 and Cu 9O -46 32 are used to investigate the correlation between highest occupied molecular orbital (HOMO) energy and T c. We observe excellent correlations between HOMO energy and oxygen stoichiometry and in turn T c and structure. It is demonstrated that CuO 2 planes are essential for superconductivity for the YBa 2Cu 3O 7- x system. Fe 3+, Zn 2+ and Ni 2+ doped CuO clusters are also investigated, and a good correlation between HOMO energy and oxygen stoichiometry is observed. Site preference of the dopants is also analyzed.