论文标题
基于部分正交化的运动截断方案方程
Equation of motion truncation scheme based on partial orthogonalization
论文作者
论文摘要
我们引入了一个一般方案，以始终如一地截断Green功能的运动方程。我们的方案可以保证具有实际的激发能和正频谱重量的物理绿色功能。我们的方案类似于均值字段参数中有免费参数，这些参数可能被确定为尽可能地获得与物理的近似值。作为测试案例，我们将方案应用于2D哈伯德模型的两极近似。在半填充时，我们找到了具有几个有趣属性的绝缘溶液：它的能量期望值较低，并且可以在大型U极限的情况下提供全部非相互作用带宽。远离半填充，尤其是在中间相互作用方案中，我们的方案允许几个不同的阶段具有不同数量的费米表面和拓扑。
We introduce a general scheme to consistently truncate equations of motion for Green's functions. Our scheme is guaranteed to generate physical Green's functions with real excitation energies and positive spectral weights. There are free parameters in our scheme akin to mean field parameters that may be determined to get as good an approximation to the physics as possible. As a test case we apply our scheme to a two-pole approximation for the 2D Hubbard model. At half-filling we find an insulating solution with several interesting properties: it has low expectation value of the energy and it gives upper and lower Hubbard bands with the full non-interacting bandwidth in the large U limit. Away from half-filling, in particular in the intermediate interaction regime, our scheme allows for several different phases with different number of Fermi surfaces and topologies.
