Invited Talk: Philipp WernerAb-initio GW+DMFT simulation of correlated materials

A proper ab-initio simulation of correlated electron materials requires a consistent description of correlations and screening. In quantum embedding approaches, this necessitates the self-consistent computation of the interaction parameters of the embedded system. A promising framework, which has been proposed 20 years ago [1], is the combination of the GW ab-initio method and dynamical mean field theory (DMFT). This fully diagrammatic scheme involves two coupled self-consistency loops for the Green's function and screened interaction, and requires the explicit treatment of dynamical screening effects. After the development of powerful impurity solvers for electron-boson systems [2], the first implementation of GW+DMFT for a single-band Hubbard model has been realized 10 years ago [3]. The method was subsequently extended into an ab-initio scheme for realistic materials simulations through the development of the multi-tier GW+DMFT approach [4,5]. This method employs a G0W0 downfolding to an intermediate energy space with O(10) bands. Within this intermediate space, correlations and screening are treated at the self-consistent GW level, while accurate local self-energies and polarizations for a subset of strongly correlated orbitals are obtained from (extended) DMFT calculations. Apart from the choice of the subspaces, multi-tier GW+DMFT is free of adjustable parameters, and thus provides a fully ab-initio description of correlated materials. Over the last years, the scheme has been extended to systems with multiple correlated atoms in the unit cell and successfully tested on a broad range of materials [6,7]. In this talk, I will give an overview of the methodological developments and the applications of the GW+DMFT framework.