Exact singlet bond ground states for electronic models

TL;DR

This paper introduces specific 1D and 2D electronic models with exact ground states represented by singlet bonds, including complex interactions like correlated hopping and spin interactions, revealing phenomena like symmetry breaking.

Contribution

It presents new electronic models with exact ground states using singlet bond wave functions, expanding understanding of correlated electron systems.

Findings

Exact ground states constructed for several models

Spontaneous translational symmetry breaking observed

Transition point between phases with and without long-range order identified

Abstract

We have proposed several 1D and 2D electronic models with the exact ground state. The ground state wave function of these models is represented in terms of "singlet bond" functions consisting of homopolar and ionic configurations. The Hamiltonians of the models include the correlated hopping of electrons, pair hopping terms and the spin interactions. One of the 1D models demonstrates spontaneous breaking of the translational symmetry. We studied also the model describing the transition point between the phases with and without an off-diagonal long-range order.