Relativistically parametrized extended Hueckel calculation of net charges on atoms in yttrium barium copper oxide (YBa2Cu3O7)

Abstract

The electronic structure of YBazCusOt has been investigated by the method of relativistically parametrized extended Hiickel (REX) calculations. Calculations have been carried out in steps, for different clusters of atoms, so as to obtain a proper picture of the charge distribution in the solid state. We have calculated the total energies of different electronic configurations for each cluster. The bulk has been simulated as a vast collection of appropriate point charges for each electronic configuration of the cluster. Interaction of the cluster with its counterion environment has been treated in the point charge interaction model. The ground-state electronic configuration has then been determined for each cluster embedded in solid. These calculations show that on average the hole has a higher probability to reside on the O(4) atoms and a lower probability to be found in the Cu( I)-O( 1) chains. These results are in good agreement with experimental observations.

Relativistic quantum chemistry and rigorous variational analysis

“…Again the reader is referred to the article by Pyykk/5 (1988) for detailed references. The REX program has recently been used to find the location of charge carriers in the normal state of YBa2Cu 30 7 superconductors (Datta et al 1993).…”