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    Université de Fribourg

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

    Ayral, Thomas ; Biermann, Silke ; Werner, Philipp ; Boehnke, Lewin

    In: Physical Review B, 2017, vol. 95, no. 24, p. 245130

    In electronic systems with long-range Coulomb interaction, the nonlocal Fock- exchange term has a band-widening effect. While this effect is included in combined many-body perturbation theory and dynamical mean field theory (DMFT) schemes, it is not taken into account in standard extended DMFT (EDMFT) calculations. Here, we include this instantaneous term in both approaches and investigate its...

    Université de Fribourg

    Extended dynamical mean-field study of the Hubbard model with long-range interactions

    Huang, Li ; Ayral, Thomas ; Biermann, Silke ; Werner, Philipp

    In: Physical Review B, 2014, vol. 90, no. 19, p. 195114

    Using extended dynamical mean-field theory and its combination with the GW approximation, we compute the phase diagrams and local spectral functions of the single-band extended Hubbard model on the square and simple cubic lattices, considering long-range interactions up to the third nearest neighbors. The longer-range interactions shift the boundaries between the metallic, charge-ordered...

    Université de Fribourg

    Screening and nonlocal correlations in the extended Hubbard model from self-consistent combined GW and dynamical mean field theory

    Ayral, Thomas ; Biermann, Silke ; Werner, Philipp

    In: Physical Review B, 2013, vol. 87, no. 12, p. 125149

    We describe a recent implementation of the combined GW and dynamical mean field method (GW+DMFT) for the two-dimensional Hubbard model with onsite and nearest-neighbor repulsion. We clarify the relation of the GW+DMFT scheme to alternative approaches in the literature, and discuss the corresponding approximations to the free-energy functional of the model. Furthermore, we describe a numerically...

    Université de Fribourg

    Spectral Properties of Correlated Materials: Local Vertex and Nonlocal Two-Particle Correlations from Combined GW and Dynamical Mean Field Theory

    Ayral, Thomas ; Werner, Philipp ; Biermann, Silke

    In: Physical Review Letters, 2012, vol. 109, no. 22, p. 226401

    We present a fully self-consistent combined GW and dynamical mean field (DMFT) study of the extended two-dimensional Hubbard model. The inclusion of the local dynamical vertex stemming from the DMFT self-energy and polarization is shown to cure the known problems of self-consistent GW. We calculate momentum-resolved spectral functions, two-particle polarizations, and electron-loss spectra, as...