Solving the multi-site and multi-orbital Dynamical Mean Field Theory using Density Matrix Renormalization

TL;DR

This paper introduces an efficient DMRG-based impurity solver for DMFT that accurately computes real-frequency response functions, enabling the study of complex multi-orbital and multi-site models with high precision.

Contribution

It develops a novel DMRG-based method for solving multi-site and multi-orbital DMFT problems with real-frequency response functions at zero temperature.

Findings

Accurate Green's functions on the real frequency axis.

Capability to handle large, complex impurity models.

Reliable calculation of non-local self energies across various parameters.

Abstract

We implement an efficient numerical method to calculate response functions of complex impurities based on the Density Matrix Renormalization Group (DMRG) and use it as the impurity-solver of the Dynamical Mean Field Theory (DMFT). This method uses the correction vector to obtain precise Green's functions on the real frequency axis at zero temperature. By using a self-consistent bath configuration with very low entanglement, we take full advantage of the DMRG to calculate dynamical response functions paving the way to treat large effective impurities such as those corresponding to multi-orbital interacting models and multi-site or multi-momenta clusters. This method leads to reliable calculations of non-local self energies at arbitrary dopings and interactions and at any energy scale.