Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden.
J Phys Condens Matter. 2012 Feb 8;24(5):055603. doi: 10.1088/0953-8984/24/5/055603. Epub 2012 Jan 17.
We propose an improved fast multi-orbital impurity solver for the dynamical mean field theory based on equations of motion (EOM) for Green's functions and a decoupling scheme. In this scheme the inter-orbital Coulomb interactions are treated fully self-consistently, and involve the inter-orbital fluctuations. As an example of the use of the derived multi-orbital impurity solver, the two-orbital Hubbard model is studied for various cases. Comparisons are made between numerical results obtained with our EOM scheme and those obtained with quantum Monte Carlo and numerical renormalization group methods. The comparison shows a good agreement, but also reveals a dissimilarity of the behaviors of the densities of states which is caused by inter-site inter-orbital hopping effects and on-site inter-orbital fluctuation effects, thus corroborating the assertion of the value of the EOM method for the study of multi-orbital strongly correlated systems.
我们提出了一种改进的快速多轨道杂质求解器，用于基于格林函数运动方程（EOM）和去耦方案的动态平均场理论。在该方案中，轨道间库仑相互作用被完全自洽地处理，并涉及轨道间涨落。作为所提出的多轨道杂质求解器的应用示例，我们研究了各种情况下的双轨道 Hubbard 模型。我们的 EOM 方案得到的数值结果与量子蒙特卡罗和数值重整化群方法得到的结果进行了比较。比较表明，存在很好的一致性，但也揭示了态密度行为的差异，这是由局域间轨道间跃迁效应和局域间轨道间涨落效应引起的，从而证实了 EOM 方法在多轨道强关联系统研究中的价值。
