A density of states approach to the hexagonal Hubbard model at finite density

Abstract

We apply the Linear Logarithmic Relaxation (LLR) method, which generalizes the Wang-Landau algorithm to quantum systems with continuous degrees of freedom, to the fermionic Hubbard model with repulsive interactions on the honeycomb lattice. We compute the generalized density of states of the average Hubbard field and divise two reconstruction schemes to extract physical observables from this result. By computing the particle density as a function of chemical potential we assess the utility of LLR in dealing with the sign problem of this model, which arises away from half filling. We show that the relative advantage over brute-force reweighting grows as the interaction strength is increased and discuss possible future improvements.

revised version, accepted for publication in Phys. Rev. D

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• Link auxiliary field method in the Extended Hubbard model
• Stochastic and Tensor Network simulations of the Hubbard Model
• Loss of ergodicity in a quantum hopping model of a dense many body system with repulsive interactions