Nearest-Neighbor Repulsion and Competing Charge and Spin Order in the Extended Hubbard Model

TL;DR

This paper extends the two-particle self-consistent approach to the extended Hubbard model, incorporating nearest-neighbor interactions, and compares its accuracy with Quantum Monte Carlo results, revealing effects on charge and spin order.

Contribution

The paper introduces a generalized TPSC method for the extended Hubbard model, including nearest-neighbor interactions, and analyzes its accuracy against Quantum Monte Carlo data.

Findings

Positive off-site interaction enhances charge fluctuations.

Nearest-neighbor interaction reduces magnetic order.

The extended TPSC aligns well with Quantum Monte Carlo results.

Abstract

We generalize the two-particle self-consistent approach (TPSC) to study the extended Hubbard model, where nearest-neighbor interaction is present in addition to the usual local screened interaction. Similarities and differences between the TPSC approach and the Singwi Tosi Land Sj\"{o}lander (STLS) approximation for the electron gas are discussed. The accuracy of our extension of TPSC is assessed by comparisons with Quantum Monte Carlo calculations of Y. Zhang and J. Callaway, Phys. Rev. B \textbf{39}, 9397 (1989). We observe that a positive off-site interaction enhances staggered charge fluctuations and reduces staggered magnetic order.