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首页> 外文会议>Conference on High Temperature Superconductivity Coral Gables, Florida January 7-13 1999 >Theory of pairing in the Cu-O plane: three-band hubbard model and beyond
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Theory of pairing in the Cu-O plane: three-band hubbard model and beyond

机译：Cu-O平面中的配对理论：三频Hubbard模型及其他

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摘要

We calculate the effective interaction W_eff) between two holes added to the ground state of the repulsive three-band Hubbard model. To make contact with Corrper theory and with earlier Hubbard model cluster studies. We first sue a per-turbative canonical transformation, to generate a two-body Hamiltonian. Then, we extend the results to all orders. The approach is exact in principle, and we obtain a closed analytic expression including explicitly the effects of all virtual transitions to 4-body intermediate states. Our sheme naturally lends itself to embody off-site, inter-planar, phonon-mediated and other interactions which are not considered in the Hubbard model but may well be important. The result depends qualitatively on the symmetry of the two-hole state: ~1B_2 and ~1A_2 pairs are special, because the bare holes do not interact by the on-site repulsion (W chemical bounds 0 pairs). The effective interaction in these channels is attractive and leads to a Cooper-like instability of the Fermi liquid; however W_(eff) is repulsive for triplet pairs. Bound two-hole states of the same nature were reorted earlier in small cluster calculations by exact diagonalisation methods; only symmetric clusters are good models of the plane. Once W_(eff) is known, the pair eigenfunction is determined by an integral equation. We present numerical estimates of the binding energy | DELTA | of the pairs, which is in the physically interesting range of tens of meV if unscreened on-site repulsion parameters are used.
机译：我们计算了两个孔之间的有效相互作用（W_eff），这些孔添加到了排斥性的三波段Hubbard模型的基态。与Corrper理论和早期的Hubbard模型聚类研究建立联系。我们首先起诉一个扰动正则变换，以生成一个两体哈密顿量。然后，我们将结果扩展到所有订单。该方法原则上是精确的，并且我们获得了一个封闭的分析表达式，其中明确包括了所有虚拟过渡到4体中间状态的影响。我们的sheme很自然地体现了场外，平面间，声子介导的和其他交互作用，这些交互作用在Hubbard模型中并未考虑，但可能很重要。结果定性地取决于两孔态的对称性：〜1B_2和〜1A_2对是特殊的，因为裸孔不通过现场排斥作用相互作用（W个化学键为0对）。在这些通道中的有效相互作用具有吸引力，并导致费米液体的库珀样不稳定性。但是W_（eff）对三联体对是排斥的。通过精确的对角化方法，在小聚类计算中更早地重新排列了具有相同性质的束缚两孔态。只有对称簇是飞机的良好模型。一旦知道了W_（eff），就通过积分方程确定对本征函数。我们给出结合能的数值估计。 DELTA |如果使用未筛选的现场排斥参数，则它们在物理上有意义的范围内为数十meV。

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