Lange Florian, Fehske Holger
Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen National High Performance Computing Center (NHR@FAU), 91058, Erlangen, Germany.
Institute of Physics, University of Greifswald, 17489, Greifswald, Germany.
Sci Rep. 2024 Aug 5;14(1):18050. doi: 10.1038/s41598-024-68811-y.
Including the previously ignored dispersion of phonons we revisit the metal-insulator transition problem in one-dimensional electron-phonon systems on the basis of a modified spinless fermion Holstein model. Using matrix-product-state techniques we determine the global ground-state phase diagram in the thermodynamic limit for the half-filled band case, and show that in particular the curvature of the bare phonon band has a significant effect, not only on the transport properties characterized by the conductance and the Luttinger liquid parameter, but also on the phase space structure of the model as a whole. While a downward curved (convex) dispersion of the phonons only shifts the Tomonaga-Luttinger-liquid to charge-density-wave quantum phase transition towards stronger EP coupling, an upward curved (concave) phonon band leads to a new phase-separated state which, in the case of strong dispersion, can even completely cover the charge-density wave. Such phase separation does not occur in the related Edwards fermion-boson model.
考虑到之前被忽略的声子色散，我们基于修正的无自旋费米子霍尔斯坦模型重新审视了一维电子 - 声子系统中的金属 - 绝缘体转变问题。使用矩阵乘积态技术，我们确定了半填充能带情况下热力学极限下的全局基态相图，并表明特别是裸声子能带的曲率不仅对以电导和卢廷格液体参数表征的输运性质有显著影响，而且对整个模型的相空间结构也有显著影响。虽然声子的向下弯曲（凸）色散仅将汤川 - 卢廷格液体到电荷密度波的量子相变向更强的电 - 声耦合方向移动，但向上弯曲（凹）的声子能带会导致一种新的相分离状态，在强色散情况下，这种状态甚至可以完全覆盖电荷密度波。这种相分离在相关的爱德华兹费米子 - 玻色子模型中不会出现。
