2023/11/15 by Kristjan Haule, Haule, Kristjan
Physics and Astronomy · #FOS: Physical sciences #Magnetic properties of thin films #Materials Science (cond-mat.mtrl-sci) #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2311.09412
openalex publication_date 2023/11/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
The diagramatic Monte Carlo method has so far been primarily used in connection with the weak coupling expansion. Here we show that the strong coupling expansion offers a significant advantage: it can be efficiently implemented on both the real and the imaginary axis at finite temperature. Using the example of a quantum impurity solver for the Dynamical Mean Field Theory (DMFT) problem, we illustrate rapid convergence with respect to the expansion order. We derive a closed-form expression for the Feynman diagrams of arbitrary order on the real axis. Employing these Feynman rules, we implement the bold hybridization-expansion quantum Monte Carlo (BHQMC) impurity solver and compare its performance to state-of-the-art results from Numerical Renormalization Group calculations of the Mott transition within DMFT applied to the Hubbard model. We demonstrate its power in providing a very precise frequency dependent scattering rate at finite temperature, enabling accurate spectroscopy calculations and delivering benchmark results for transport within DMFT.