Perturbative solution of fermionic sign problem in lattice Quantum Monte Carlo

Abstract

We develop a strong-coupling perturbation scheme for a generic Hubbard model around a half-filled particle-hole-symmetric reference system, which is free from the fermionic sign problem. The approach is based on the lattice determinantal Quantum Monte Carlo (QMC) method in continuous and discrete time versions for large periodic clusters in a fermionic bath. Considering the first-order perturbation in the shift of the chemical potential and of the second-neighbour hopping gives an accurate electronic spectral function for a parameter range corresponding to the optimally doped cuprate system for temperature of the order of $T=0.1t$, the region hardly accessible for the straightforward lattice QMC calculations. We discuss the formation of the pseudogap and the nodal-antinodal dichotomy for a doped Hubbard system in a strong-coupling regime with the interaction parameter $U$ equal to the bandwidth and the optimal value of the next-nearest-neighbor hopping parameter $t'$ for high-temperature superconducting cuprates.