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首页> 外文期刊>Philosophical magazine, B. Physics of condensed matter, electronic, optical, and magnetic properties >Exact results for the optical absorption of strongly correlated electrons in a half-filled Peierls-distorted chain
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Exact results for the optical absorption of strongly correlated electrons in a half-filled Peierls-distorted chain

机译：精确计算半填充Peierls扭曲链中强相关电子的光吸收结果

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In this, the second of three articles on the optical absorption of electrons in a half-filled Peierls-distorted chain, we present exact results for strongly correlated tight-binding electrons. In the limit of a strong on-site interaction U, we map the Hubbard model onto the Harris-Lange model which can be solved exactly in one dimension in terms of spinless fermions for the charge excitations. The exact solution allows for an interpretation of the charge dynamics in terms of parallel Hubbard bands with a free-electron dispersion of bandwidth W, separated by the Hubbard interaction U. The spin degrees of freedom enter the expressions for the optical absorption only via a momentum-dependent but static ground-state expectation value. The remaining spin problem can be traced out exactly since the eigenstates of the Harris-Lange model are spin degenerate. This corresponds to the Hubbard model at temperatures large compared with the spin exchange energy. Explicit results are given for the optical absorption in the presence of a lattice distortion delta and a nearest-neighbour interaction V. We find that the optical absorption for V = 0 is dominated by a peak at omega = U and broad but weak absorption bands for omega - U less than or equal to W. For an appreciable nearest-neighbour interaction V > W/2, almost all the spectral weight is transferred to Simpson's exciton band which is eventually Peierls split.
机译：在本文中，有关半填充Peierls扭曲链中电子的光吸收的三篇文章中的第二篇，我们为紧密相关的紧密结合电子提供了精确的结果。在强大的现场交互作用U的限制下，我们将Hubbard模型映射到Harris-Lange模型上，该模型可以精确地在一维上根据电荷激发的无旋转费米子求解。精确的解决方案可以用平行的Hubbard波段，具有自由电子色散W，由Hubbard相互作用U隔开的，平行的Hubbard波段来解释电荷动力学。自旋自由度仅通过动量输入光吸收的表达式依赖但静态的基态期望值。由于Harris-Lange模型的本征态是自旋简并的，因此可以精确地找出剩余的自旋问题。与自旋交换能量相比，这在较大温度下对应于Hubbard模型。在存在晶格畸变δ和最近邻相互作用V的情况下，给出了明确的光吸收结果。我们发现，V = 0的光吸收主要由ω= U处的峰和宽而弱的吸收带决定。 omega-U 小于或等于W。对于明显的近邻相互作用V> W / 2，几乎所有光谱权重都转移到辛普森的激子带，最终由Peierls分裂。

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