Journal article

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

  • Ayral, Thomas Theoretische Physik, ETH Zurich, Switzerland - Centre de Physique Théorique, Ecole Polytechnique, Palaiseau, France - Institut de Physique Théorique (IPhT), Gif-sur-Yvette, France
  • Biermann, Silke Centre de Physique Théorique, Ecole Polytechnique, Palaiseau, France - Japan Science and Technology Agency, Kawaguchi, Japan
  • Werner, Philipp Theoretische Physik, ETH Zurich, Switzerland - Department of Physics, University of Fribourg, Switzerland
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  • Physical Review B. - 2013, vol. 87, no. 12, p. 125149
English 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 exact technique for the solution of the GW+DMFT equations, namely, the hybridization expansion continuous-time algorithm for impurity models with retarded interactions. We compute the low-temperature phase diagram of the half-filled extended Hubbard model, addressing the metal-insulator transition at small intersite interactions and the transition to a charge-ordered state for stronger intersite repulsions. GW+DMFT introduces a nontrivial momentum dependence into the many-body self-energy and polarization. We find that the charge fluctuations included in the present approach have a larger impact on the latter than on the former. Finally, within the GW+DMFT framework, as in extended DMFT, the intersite repulsion translates into a frequency dependence of the local effective interaction. We analyze this dependence and show how it affects the local spectral function.
Faculté des sciences et de médecine
Département de Physique
  • English
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