Exact Ground States of the Extended Hubbard Model on the Kagome lattice

TL;DR

This paper derives exact ground states of a generalized Hubbard model on the Kagome lattice, revealing Ne9el order and analyzing entanglement, supported by numerical methods.

Contribution

It constructs exact ground states for the extended Hubbard model on the Kagome lattice using projection operators, a novel analytical approach.

Findings

Exact plaquette-ordered ground states identified

Parameter regions for ground states determined

Entanglement entropy calculated and analyzed

Abstract

We discuss the exact plaquette-ordered ground states of the generalized Hubbard model on the Kagom\'e lattice for several fillings, by constructing the Hamiltonian as a sum of products of projection operators for up and down spin sectors. The obtained exact ground states are interpreted as N\'eel ordered states on the bond-located electrons. We determine several parameter regions of the exact ground states, and calculate the entanglement entropy. We examine the above results by numerical calculations based on exact diagonalization and density-matrix renormalization group methods.