Real-frequency TPSC+DMFT investigation of the square-lattice Hubbard model

TL;DR

This paper presents a real-frequency TPSC+DMFT method to study the 2D Hubbard model, effectively capturing pseudogap phenomena, nonlocal fluctuations, and Mott insulating states, bridging weak and strong coupling regimes.

Contribution

It introduces a hybrid TPSC+DMFT approach that combines nonlocal and local correlations in a real-frequency framework for the Hubbard model.

Findings

Accurately describes pseudogap physics and nonlocal fluctuations.

Reproduces Mott insulating behavior at high interaction strengths.

Captures evolution of Fermi pockets into Fermi arcs in doped systems.

Abstract

We investigate the two-dimensional Hubbard model using a real-frequency implementation of the TPSC+DMFT approach. This hybrid method combines the nonlocal correlations captured by the Two-Particle Self-Consistent (TPSC) approach with the local dynamical correlations of Dynamical Mean-Field Theory (DMFT). The results demonstrate that TPSC+DMFT effectively describes pseudogap physics and nonlocal fluctuations in the moderately correlated regime, while also reproducing the Mott insulating state at larger interaction strengths. For doped Mott insulators, we find that TPSC+DMFT captures the evolution of Fermi pockets into Fermi arcs, consistent with the results from cluster DMFT and photoemission studies. These findings highlight the capability of TPSC+DMFT to bridge the gap between weak and strong coupling physics in Hubbard models, providing insights into spin and charge fluctuations, as well as their role in the pseudogap formation.