Lewin Boehnke

Orthogonal polynomial representation of imaginary-time Green's functions

We study the expansion of single-particle and two-particle imaginary-time Matsubara Greens functions of quantum impurity models in the basis of Legendre orthogonal polynomials. We discuss various applications within the dynamical mean-field theory (DMFT) framework. The method provides a more compact representation of the Greens functions than standard Matsubara frequencies, and therefore significantly reduces the memory-storage size of these quantities. Moreover, it can be used as an efficient noise filter for various physical quantities within the continuous-time quantum Monte Carlo impurity solvers recently developed for DMFT and its extensions. In particular, we show how to use it for the computation of energies in the context of realistic DMFT calculations in combination with the local density approximation to the density functional theory (LDA+DMFT) and for the calculation of lattice susceptibilities from the local irreducible vertex function.

Formation of orbital-selective electron states in LaTiO3/SrTiO3 superlattices

The interface electronic structure of correlated LaTiO

Multitier self-consistent GW+EDMFT

_3

Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory

/SrTiO

Competing orders in NaxCoO2from strong correlations on a two-particle level

_3

Nonequilibrium

superlattices is investigated by means of the charge self-consistent combination of the local density approximation (LDA) to density functional theory (DFT) with dynamical mean-field theory (DMFT). Utilizing a pseudopotential technique together with a continuous-time quantum Monte-Carlo approach, the resulting complex multiorbital electronic states are addressed in a coherent fashion beyond static mean-field. General structural relaxations are taken into account on the LDA level and cooperate with the driving forces from strong electronic correlations. This alliance leads to an Ti(

GW+\mathrm{EDMFT}

3d_{xy}

: Antiscreening and Inverted Populations from Nonlocal Correlations

) dominated low-energy quasiparticle peak and a lower Hubbard band in line with photoemission studies. Furthermore correlation effects close to the band-insulating bulk SrTiO

Multi-orbital nature of the spin fluctuations in Sr2RuO4

_3

Considerable nonlocal electronic correlations in strongly doped NaxCoO2

limit as well as the Mott-insulating bulk LaTiO