Augmented hybrid exact-diagonalization solver for dynamical mean field theory

TL;DR

This paper introduces an enhanced exact diagonalization approach for solving the Anderson impurity model within dynamical mean-field theory, combining Lanczos and cluster perturbation techniques for improved spectral accuracy.

Contribution

It develops a novel hybrid method that refines the exact diagonalization solver, enabling more accurate spectral functions and full d-orbital calculations in Hubbard models.

Findings

Improved spectral function accuracy for the Hubbard model

Reliable approach for full d-orbital manifold calculations

Enhanced solver efficiency and precision

Abstract

We present a new methodology to solve the Anderson impurity model, in the context of dynamical mean-field theory, based on the exact diagonalization method. We propose a strategy to effectively refine the exact diagonalization solver by combining a finite-temperature Lanczos algorithm with an adapted version of the cluster perturbation theory. We show that the augmented diagonalization yields an improved accuracy in the description of the spectral function of the single-band Hubbard model and is a reliable approach for a full d-orbital manifold calculation.