Bandstructure meets many-body theory: The LDA+DMFT method

TL;DR

This paper introduces the LDA+DMFT method, combining density functional theory and dynamical mean field theory, to accurately model strongly correlated materials like LaMnO_3, capturing diverse electronic phases and phenomena.

Contribution

The paper presents the development and application of the LDA+DMFT approach, integrating bandstructure and many-body theories for ab initio treatment of strongly correlated materials.

Findings

Successfully modeled LaMnO_3 and its colossal magnetoresistance.

Demonstrated the method's ability to capture metal-insulator transitions.

Discussed the advantages and limitations of LDA+DMFT.

Abstract

Ab initio calculation of the electronic properties of materials is a major challenge for solid state theory. Whereas the experience of forty years has proven density functional theory (DFT) in a suitable, e.g. local approximation (LDA) to give a satisfactory description in case electronic correlations are weak, materials with strongly correlated, say d- or f-electrons remain a challenge. Such materials often exhibit colossal responses to small changes of external parameters such as pressure, temperature, and magnetic field, and are therefore most interesting for technical applications. Encouraged by the success of dynamical mean field theory (DMFT) in dealing with model Hamiltonians for strongly correlated electron systems, physicists from the bandstructure and many-body communities have joined forces and have developed a combined LDA+DMFT method for treating materials with strongly correlated electrons ab initio. As a function of increasing Coulomb correlations, this new approach yields a weakly correlated metal, a strongly correlated metal, or a Mott insulator. In this paper, we introduce the LDA+DMFT by means of an example, LaMnO_3 . Results for this material, including the colossal magnetoresistance of doped manganites are presented. We also discuss advantages and disadvantages of the LDA+DMFT approach.