State-of-the-art techniques for calculating spectral functions in models for correlated materials

TL;DR

This paper reviews advanced computational techniques for calculating spectral functions in strongly correlated materials, highlighting recent improvements using DMRG and MPS methods within the DMFT framework.

Contribution

It provides a comprehensive comparison of standard and new algorithms for spectral function calculations, demonstrating their effectiveness on the two-band Hubbard model.

Findings

DMRG and MPS methods significantly improve spectral function calculations.

New techniques outperform traditional methods in accuracy and efficiency.

Examples on the two-band Hubbard model illustrate these advancements.

Abstract

The dynamical mean field theory (DMFT) has become a standard technique for the study of strongly correlated models and materials overcoming some of the limitations of density functional approaches based on local approximations. An important step in this method involves the calculation of response functions of a multiorbital impurity problem which is related to the original model. Recently there has been considerable progress in the development of techniques based on the density matrix renormalization group (DMRG) and related matrix product states (MPS) implying a substantial improvement to previous methods. In this article we review some of the standard algorithms and compare them to the newly developed techniques, showing examples for the particular case of the half-filled two-band Hubbard model.