Analytic continuation-free Green's function approach to correlated electronic structure calculations

TL;DR

This paper introduces a new Green's function approach for correlated electronic structure calculations that avoids the ill-posed analytic continuation, improving numerical accuracy and efficiency in combining DFT with DMFT.

Contribution

A novel charge self-consistent scheme integrating DFT and DMFT using Green's functions on the Matsubara axis without analytic continuation.

Findings

Accurate spectral functions for transition metals and compounds

Agreement with Hamiltonian-based LDA+DMFT results

Enhanced numerical stability and simplicity

Abstract

We present a new charge self-consistent scheme combining Density Functional and Dynamical Mean Field Theory, which uses Green's function of multiple scattering-type. In this implementation the many-body effects are incorporated into the Kohn-Sham iterative scheme without the need for the numerically ill-posed analytic continuation of the Green's function and of the self-energy. This is achieved by producing the Kohn-Sham Hamiltonian in the sub-space of correlated partial waves and allows to formulate the Green's function directly on the Matsubara axis. The spectral moments of the Matsubara Green's function enable us to put together the real space charge density, therefore the charge self-consistency can be achieved. Our results for the spectral functions (density of states) and equation of state curves for transition metal elements, Fe, Ni and FeAl compound agree very well with those of Hamiltonian based LDA+DMFT implementations. The current implementation improves on numerical accuracy, requires a minimal effort besides the multiple scattering formulation and can be generalized in several ways that are interesting for applications to real materials.