arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1910.01792cond-mat.str-el
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二维Hubbard-Holstein模型零温相的非高斯精确对角化研究

Zero-Temperature Phases of the 2D Hubbard-Holstein Model: A Non-Gaussian Exact Diagonalization Study

Yao Wang, Ilya Esterlis, Tao Shi, J. Ignacio Cirac, Eugene Demler

摘要:

我们提出了一种数值方法,它嵌入变分非高斯波函数的方法在精确对角化,允许有效的治疗相关系统的电子-电子和电子-声子相互作用。使用广义极化子变换,我们构造了一个变分波函数,吸收电子和声子之间的纠缠到变分非高斯变换;精确对角化,然后用来处理波函数的电子部分,从而考虑到高阶相关效应超出高斯水平。保持完整的电子希尔伯特空间,复杂性仅增加了一个多项式的比例因子相对于纯电子的精确对角化计算。作为一个例子,我们用这种方法研究了二维Hubbard-Holstein模型的基态性质,证明了自旋有序态和电荷有序态之间存在干涉相.特别是,我们发现其中一个介入相具有很强的电荷磁化率和结合能,但不同于电荷密度波有序态,而另一个介入相在弱耦合下显示超导性。这种方法作为一个通用的框架,可以扩展到处理激发态和动力学,以及广泛的系统,电子-电子和电子-玻色子相互作用。

英文摘要:

We propose a numerical method which embeds the variational non-Gaussian wavefunction approach within exact diagonalization, allowing for efficient treatment of correlated systems with both electron-electron and electron-phonon interactions. Using a generalized polaron transformation, we construct a variational wavefunction that absorbs entanglement between electrons and phonons into a variational non-Gaussian transformation; exact diagonalization is then used to treat the electronic part of the wavefunction exactly, thus taking into account high-order correlation effects beyond the Gaussian level. Keeping the full electronic Hilbert space, the complexity is increased only by a polynomial scaling factor relative to the exact diagonalization calculation for pure electrons. As an example, we use this method to study ground-state properties of the two-dimensional Hubbard-Holstein model, providing evidence for the existence of intervening phases between the spin and charge-ordered states. In particular, we find one of the intervening phases has strong charge susceptibility and binding energy, but is distinct from a charge-density-wave ordered state, while the other intervening phase displays superconductivity at weak couplings. This method, as a general framework, can be extended to treat excited states and dynamics, as well as a wide range of systems with both electron-electron and electron-boson interactions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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