Elastic and coulombic contributions to real-space hole pairing in doped La2CuO4

Abstract

The energetics of three types of possible polaron pair in doped La₂CuO₄ have been investigated by computer-simulation techniques based on lattice-energy minimisation. The most energetically favourable pairing configurations have been obtained. O^–—O^– pairing is calculated to be bound by 0.119 eV. For Cu³⁺—Cu³⁺ and Cu³⁺—O^– pairing, interlayer configurations are found to be more favourable than intralayer pairing and the nearest-neighbour pairing is unfavourable. The binding energy of the pairs is found to be related to the pair distance and geometry of the pair. The Coulomb repulsive energy between hole pairs is estimated and the interlayer pairing is found to be more effective at screening Coulomb interactions between holes. The lattice distortion energy caused by polaron pairing is estimated and is taken into account in the calculation.