论文标题
相关系统中光激发的示意研究
Diagrammatic study of optical excitations in correlated systems
论文作者
论文摘要
光导率包含有关相关电子系统属性的相关信息。在无限的尺寸中，动态平均场理论变得精确，可以忽略顶点校正，并根据粒子孔气泡计算的电导率。一个有趣的问题涉及有限维系统中最相关的顶点校正的性质和效果。最近的一项数值研究表明，带有波矢量π的有序不稳定性附近的主要顶点校正来自垂直阶梯，类似于Maki-Thompson图。由于该梯形图的RPA版本（称为π-TON）可以很容易地进行评估，因此这表明了一个简单的程序，可以将抗磁性或电荷密度波波动掺入光学电导率和相关敏感性的动态平均场估计中。考虑到π-TON的π-TON和双向扩展，我们为半填充的Hubbard模型实施了此过程，并揭示了这些顶点校正的光谱特征。
The optical conductivity contains relevant information on the properties of correlated electron systems. In infinite dimensions, where dynamical mean field theory becomes exact, vertex corrections can be neglected and the conductivity computed from particle-hole bubbles. An interesting question concerns the nature and effect of the most relevant vertex corrections in finite-dimensional systems. A recent numerical study showed that the dominant vertex correction near an ordering instability with wave vector π comes from a vertical ladder, analogous to the Maki-Thompson diagram. Since the RPA version of this ladder diagram, dubbed π-ton, can be easily evaluated, this suggests a simple procedure for incorporating antiferromagnetic or charge density wave fluctuations into dynamical mean field estimates of the optical conductivity and related susceptibilities. We implement this procedure for the half-filled Hubbard model, considering the π-ton and a double-ladder extension of the π-ton, and reveal the spectral signatures of these vertex corrections.
