Superconductivity in an exactly solvable Hubbard model with bond-charge interaction

TL;DR

This paper presents an exact solution for a one-dimensional Hubbard model with bond-charge interaction, revealing superconducting ground states for moderate interactions and providing insights into its phase diagram across dimensions.

Contribution

It introduces an exactly solvable Hubbard model with bond-charge interaction at the special case t=X, and analyzes its phase diagram and superconducting properties.

Findings

Superconducting ground states for moderate U

Exact solution in one dimension at t=X

Qualitative phase diagram in arbitrary dimensions

Abstract

The Hubbard model with an additional bond-charge interaction $X$ is solved exactly in one dimension for the case $t=X$ where $t$ is the hopping amplitude. In this case the number of doubly occupied sites is conserved. In the sector with no double occupations the model reduces to the $U=\infty$ Hubbard model. In arbitrary dimensions the qualitative form of the phase diagram is obtained. It is shown that for moderate Hubbard interactions $U$ the model has superconducting ground states.