Semideterministic and stochastic sampling of Feynman diagrams with 1/N_{f} expansions
We introduce a family of (semi)-bold-line series, assisted with 1/N_{f} expansions, with N_{f} being the number of fermion flavors. If there is no additional N_{f} cut, the series reduces to the random phase approximation series in the density-density channel, complementary to the particle-hole and...
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2025-05-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.7.023177 |
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| Summary: | We introduce a family of (semi)-bold-line series, assisted with 1/N_{f} expansions, with N_{f} being the number of fermion flavors. If there is no additional N_{f} cut, the series reduces to the random phase approximation series in the density-density channel, complementary to the particle-hole and particle-particle channels introduced in Phys. Rev. B 102, 195122 (2020)2469-995010.1103/PhysRevB.102.195122. To address the very localized integrands in diagrammatic Monte Carlo, we introduced an innovative VEGAS-RG-MCMC sampling method, where we found a significant decrease of autocorrelation time without the usage of the state-of-the-art many-configuration MCMC (MCMCMC) method while the combination of both is also straightforward. We performed extensive benchmarks for density, energy, and pressure with the t-t^{′} SU(N_{f}) Hubbard model on a square lattice and honeycomb lattices over a wide range of numerical methods. For benchmark purposes, we also implement bare-U symmetry-broken perturbation series for the two-dimensional SU(2) Hubbard model on the honeycomb lattice, where we found encouraging results from weak to intermediate couplings. |
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| ISSN: | 2643-1564 |