Time-dependent Gutzwiller theory of pairing fluctuations in the Hubbard model

TL;DR

This paper introduces a method to compute pairing fluctuations in the Hubbard model using an extended Gutzwiller approximation, improving the accuracy of dynamical pairing correlations predictions for superconductivity and related phenomena.

Contribution

The paper develops a charge-rotational invariant Gutzwiller-based approach to include pairing fluctuations, providing a more accurate framework than standard Hartree-Fock methods.

Findings

Significant improvement in dynamical pairing correlations for s- and d-wave symmetries.

Better agreement with exact diagonalizations compared to Hartree-Fock ladder approximation.

Potential applications in superconductivity, Auger spectroscopy, and cold atom physics.

Abstract

We present a method to compute pairing fluctuations on top of the Gutzwiller approximation (GA). Our investigations are based on a charge-rotational invariant GA energy functional which is expanded up to second order in the pair fluctuations. Equations of motion for the fluctuations lead to a renormalized ladder type approximation. Both spectral functions and corrections to static quantities, like the ground-state energy, are computed. The quality of the method is examined for the single-band Hubbard model where we compare the dynamical pairing correlations for s- and d-wave symmetries with exact diagonalizations and find a significant improvement with respect to analogous calculations done within the standard Hartree-Fock ladder approximation. The technique has potential applications in the theory of Auger spectroscopy, superconductivity, and cold atom physics.