20.500.12556/RUL-177292 Automated evaluation of imaginary time strong coupling diagrams by sum-of-exponentials hybridization fitting We present an efficient separation of variables algorithm for the evaluation of imaginary time Feynman diagrams appearing in the bold pseudo-particle strong coupling expansion of the Anderson impurity model. The algorithm uses a fitting method based on AAA rational approximation and numerical optimization to obtain a sum-of-exponentials expansion of the hybridization function, which is then used to decompose the diagrams. A diagrammatic formulation of the algorithm leads to an automated procedure for diagrams of arbitrary order and topology. We also present methods of stabilizing the self-consistent solution of the pseudo-particle Dyson equation. The result is a low-cost and high-order accurate impurity solver for quantum embedding methods using general multi-orbital hybridization functions at low temperatures, appropriate for low-to-intermediate expansion orders. In addition to other benchmark examples, we use our solver to perform a dynamical mean-field theory study of a minimal model of the strongly correlated compound Ca$_2$RuO$_4$, describing the anti-ferromagnetic transition and the in- and out-of-plane anisotropy induced by spin-orbit coupling. condensed matter physics quantum physics many-body systems Hubbard model Anderson model fizika kondenzirane snovi kvantna fizika večdelčni sistemi Hubbardov model Andersonov model true false true Angleški jezik Slovenski jezik Članek v reviji 2025-12-19 14:04:31 2025-12-19 14:04:34 2025-12-29 04:17:37 0000-00-00 00:00:00 2025 0 0 39 str. iss. 5 Vol. 19 Nov. 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 538.9 2542-4653 10.21468/SciPostPhys.19.5.121 262306819 SciPostPhys_19_5_121.pdf SciPostPhys_19_5_121.pdf 1 A12BC4D3E2BA8EB69C3168FC5DC0DEA2 bb5ac12b7020bf6ab51fb560a3c68567470788f7dc6b1c47c99d0812c2afba61 1bb6f7a8-dcdb-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=224250 https://scipost.org/10.21468/SciPostPhys.19.5.121 0 231c8b61-dcdb-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=224251 Fakulteta za matematiko in fiziko 0 0 0