Electron paramagnetic resonance response of Cu3+ in D 4h coordination symmetry

Theoretical calculations of the wavefunctions and energy level structure of the 3F ion with a 3d8 electronic configuration in a D4h distorted Oh weak crystal field, including the spin-orbit interaction, indicate the possible paramagnetic features of strongly distorted octahedrally coordinated Cu3+ ions, up to the square-planar coordination. The Zeeman matrices are evaluated over all the states of the ion in order to calculate the generalized Van Vleck susceptibility and the EPR transition probabilities. It is shown that no paramagnetic resonance should be expected for sufficiently large distortions, even when the system possesses a non-null magnetic moment. These results may contribute to the interpretation of several EPR experimental data on copper oxides whose meaning has been in many cases misunderstood.