Superconducting ground state of the two-dimensional Hubbard model: a variational study

TL;DR

This paper introduces a refined variational wave function to study d-wave superconductivity in the 2D Hubbard model, revealing insights into the ground state and pairing mechanisms.

Contribution

The study proposes a novel variational wave function that improves upon previous models by enhancing hole delocalization and inducing kinetic exchange, leading to better energy estimates.

Findings

Large energy gain from the new wave function

Weak influence of additional terms on pairing

Insights into the superconducting ground state

Abstract

A trial wave function is proposed for studying the instability of the two-dimensional Hubbard model with respect to d-wave superconductivity. Double occupancy is reduced in a similar way as in previous variational studies, but in addition our wave function both enhances the delocalization of holes and induces a kinetic exchange between the electron spins. These refinements lead to a large energy gain, while the pairing appears to be weakly affected by the additional term in the variational wave function.