Hole-pairing mechanisms in La2CuO4

Abstract
The authors consider various possible hole-coupling mechanisms in the high-Tc superconductor, doped La2CuO4. Negative-U processes are energetically unfavourable. It is possible that bipolaronic species may be stabilised when antiferromagnetic energies and coupling terms arising from the distortions of the CuO6 octahedra are taken into account.