论文标题
超越累积近似值：功率序列校正到荷斯坦系统中的单个粒子函数
Going Beyond the Cumulant Approximation: Power Series Correction to Single Particle Green's Function in Holstein System
论文作者
论文摘要
在单个电子的背景下，两个轨道荷斯坦系统与无散的玻色子结合在一起，我们开发了一种使用功率序列校正（PSC）方案校正单个粒子绿色功能的通用方法。然后，我们通过PSC方案概述了累积近似的各种口味，并解释其背后的假设和近似值。最后，我们将PSC光谱函数与累积和确切的对角光谱函数进行了比较，并阐明了该问题的三个方案 - 两个累积解释，一个累积液失败的地方。我们发现，确切的和PSC光谱函数匹配在所有三个方案中的光谱扩展中。
In the context of a single electron two orbital Holstein system coupled to dispersionless bosons, we develop a general method to correct single particle Green's function using a power series correction(PSC) scheme. We then outline the derivations of various flavors of cumulant approximation through the PSC scheme and explain the assumptions and approximations behind them. Finally, we compute and compare PSC spectral function with cumulant and exact diagonalized spectral functions and elucidate three regimes of this problem - two that cumulant explains and one where cumulant fails. We find that the exact and the PSC spectral functions match within spectral broadening across all three regimes.
