Electronic Hamiltonian and antiferromagnetic interactions in La2CuO4
A many-body Hamiltonian for La2CuO4 with ab initio parameters is solved numerically using embedded-cluster approximations. The results give an antiferromagnetic insulator with a 2-3 eV energy gap, consistent with spectroscopic measurements, NMR chemical shifts, and the spin-wave velocity. The Néel state has a significant frustration due to second-neighbor interactions, J2/J1≊5%-8%. Two competing states are found for holes introduced by doping, with primarily in-plane oxygen pσ and out-of-plane oxygen pz character.
Phys. Rev. B 40, 2620-2623 (1989)