Electronic Structure Calculations with LDA+DMFT

TL;DR

The paper discusses the LDA+DMFT method, combining density-functional theory with dynamical mean-field theory, to study strongly correlated materials, highlighting its core steps, approximations, and a typical application.

Contribution

It introduces the core aspects of the LDA+DMFT method and demonstrates a prototypical application for strongly correlated materials.

Findings

Effective combination of ab-initio and many-body techniques

Identification of key approximations and computational challenges

Successful application to a model strongly correlated material

Abstract

The LDA+DMFT method is a very powerful tool for gaining insight into the physics of strongly correlated materials. It combines traditional ab-initio density-functional techniques with the dynamical mean-field theory. The core aspects of the method are (i) building material-specific Hubbard-like many-body models and (ii) solving them in the dynamical mean-field approximation. Step (i) requires the construction of a localized one-electron basis, typically a set of Wannier functions. It also involves a number of approximations, such as the choice of the degrees of freedom for which many-body effects are explicitly taken into account, the scheme to account for screening effects, or the form of the double-counting correction. Step (ii) requires the dynamical mean-field solution of multi-orbital generalized Hubbard models. Here central is the quantum-impurity solver, which is also the computationally most demanding part of the full LDA+DMFT approach. In this chapter I will introduce the core aspects of the LDA+DMFT method and present a prototypical application.