Semi-Deterministic and Stochastic Sampling of Feynman Diagrams with 1/N_f Expansions

2024/09/03 by Shi, Boyuan · 1 citation
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)

paper · doi:10.48550/arxiv.2409.02032

Abstract

We introduce a family of (semi) bold-line series, assisted with 1/N_f expansions, with N_f being the number of fermion flavours. If there is no additional N_f cut, the series reduces to the RPA series in the density-density channel, complementary to the particle-hole and particle-particle channels introduced in [Phys. Rev. B 102, 195122 (2020)]. We performed extensive benchmarks for density, energy and pressure with t-t' SU(N_f) Hubbard model on 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 2D SU(2) Hubbard model on the honeycomb lattice, where we found encouraging results from weak to intermediate couplings.

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