Dynamical vertex approximation for the two-dimensional Hubbard model

Superconductivity in the two-dimensional Hubbard model.

A refined variational wave function for the two-dimensional repulsive Hubbard model is studied numerically , with the aim of approaching the difficult crossover regime of intermediate values of U. The issue of a superconducting ground state with d-wave symmetry is investigated for an average electron density n ≈ 0.8 and for U = 8t. Due to finite-size effects a clear-cut answer to this fundament...

Dynamical cluster approximation study of the anisotropic two-orbital Hubbard model.

We investigate the properties of a two-orbital Hubbard model with unequal bandwidths on the square lattice in the framework of the dynamical cluster approximation (DCA) combined with a continuous-time quantum Monte Carlo algorithm. We explore the effect of short-range spatial fluctuations on the nature of the metal-insulator transition and the possible occurrence of an orbital-selective Mott tr...

Dynamical vertex approximation for nanoscopic systems.

With an increasing complexity of nanoscopic systems and the modeling thereof, new theoretical tools are needed for a reliable calculation of complex systems with strong electronic correlations. To this end, we propose a new approach based on the recently introduced dynamical vertex approximation. We demonstrate its reliability already on the one-particle vertex (i.e., dynamical mean field theor...

Beyond extended dynamical mean-field theory: Dual boson approach to the two-dimensional extended Hubbard model

Two-dimensional Hubbard model: Numerical simulation study.

We have studied the two-dimensional Hubbard model on a square lattice with nearest-neighbor hopping. We first discuss the properties of the model within the mean-field approximation: Because of the form of the band structure, some peculiar features are found. We then discuss the simulation algorithm used and compare simulation results with exact results for 6-site chains to test the reliability...