论文标题
动态群集近似中的连续动量依赖性
Continuous momentum dependence in the dynamical cluster approximation
论文作者
论文摘要
动力簇近似（DCA）是单位动力学平均场理论的量子群集扩展，该均值均值场理论在系统和非扰动上在空间非局部动态相关上融合。 DCA $^+$ $算法通过引入晶格自我能源和连续的动量依赖性来解决DCA的群集形状依赖性，并通过群集大小提高了群集大小。但是，我们表明，当使用Bare Green的群集函数制定了dca $^+$ $算法的基本问题时，就会受到基本问题的困扰。在低兴奋剂时，DCA $^+$能源在低掺杂时的紧密相关性方面最严重，并且在其中持续到标准DCA长期融合的群集大小。鉴于DCA $^+$算法的失败，我们建议使用单粒子和两颗粒相关功能的交互后进行DCA模拟，以保留连续动量依赖性以及DCA中相关的益处。我们证明了这种实用方法的有效性，并为半填充和孔洞的二维Hubbard模型的结果提供了有效性。
The dynamical cluster approximation (DCA) is a quantum cluster extension to the single-site dynamical mean-field theory that incorporates spatially nonlocal dynamic correlations systematically and nonperturbatively. The DCA$^+$ algorithm addresses the cluster shape dependence of the DCA and improves the convergence with cluster size by introducing a lattice self-energy with continuous momentum dependence. However, we show that the DCA$^+$ algorithm is plagued by a fundamental problem when its self-consistency equations are formulated using the bare Green's function of the cluster. This problem is most severe in the strongly correlated regime at low doping, where the DCA$^+$ self-energy becomes overly metallic and local, and persists to cluster sizes where the standard DCA has long converged. In view of the failure of the DCA$^+$ algorithm, we propose to complement DCA simulations with a post-interpolation procedure for single-particle and two-particle correlation functions to preserve continuous momentum dependence and the associated benefits in the DCA. We demonstrate the effectiveness of this practical approach with results for the half-filled and hole-doped two-dimensional Hubbard model.
