Electronic states of LaCuO system are calculated from the first principles, using the MCSCF-CI method and by taking CuO6 and Cu2O11 clusters as a model. For CuO6 it is shown that the electronic states are very sensitive to the distance between the apical oxygen and copper atoms, which becomes shorter with doping divalent ions. For Cu2O11 it is shown in the undoped case that two electrons are localized in copper dx2-y2 orbitals and make anti-ferromagnetic coupling with exchange integral J of 1600 K. When a hole is doped, we show that a doped hole spends 39 % of time at copper sites while 61 % at oxygen sites. This is due to the energy gain arising from direct anti-ferromagnetic exchange between Cu and O unpaired spins which results in ferromagnetic spin-coupling between Cu spins.
ASJC Scopus subject areas
- 化学 (全般)