Intersite electron correlations in a Hubbard model on inhomogeneous lattices

TL;DR

This paper investigates how short-range intersite electron correlations influence the Mott transition in a Hubbard model on inhomogeneous lattices, using a real-space dual fermion approach to match quantum Monte Carlo results.

Contribution

It introduces a real-space dual fermion method to analyze intersite correlations in inhomogeneous Hubbard models, highlighting their impact on the Mott transition.

Findings

Nearest-neighbor correlations significantly lower the critical U for the Mott transition.

The critical interaction U/t is approximately 6.4, consistent with quantum Monte Carlo results.

Short-range intersite correlations are crucial for accurately describing the transition.

Abstract

We study intersite electron correlations in the half-filled Hubbard model on square lattices with periodic and open boundary conditions by means of a real-space dual fermion approach. By calculating renormalization factors, we clarify that nearest-neighbor intersite correlations already significantly reduce the critical interaction. The Mott transition occurs at U/t~6.4, where $U$ is the interaction strength and t is the hopping integral. This value is consistent with the quantum Monte Carlo results. This shows the importance of short-range intersite correlations, which are taken into account in the framework of the real-space dual fermion approach.