Flow to strong coupling in the two-dimensional Hubbard model

Flow to strong coupling in the two-dimensional Hubbard model

We extend the analysis of the renormalization group flow in the two-dimensional Hubbard model close to half-filling using the recently developed temperature flow formalism. We investigate the interplay of d-density wave and Fermi surface deformation tendencies with those towards d-wave pairing and antiferromagnetism. For a ratio of next nearest to nearest neighbor hoppings, t′/t = −0.25, and ba...

Hole dynamics in the two-dimensional strong-coupling Hubbard Hamiltonian.

Strong-coupling perturbation theory for the two-dimensional Bose-Hubbard model in a magnetic field

The Bose-Hubbard model in an external magnetic field is investigated with strong-coupling perturbation theory. The lowest-order secular equation leads to the problem of a charged particle moving on a lattice in the presence of a magnetic field, which was first treated by Hofstadter. We present phase diagrams for the two-dimensional square and triangular lattices, showing a change in shape of th...

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...

Strong-coupling perturbation theory of the Hubbard model

The strong-coupling perturbation theory of the Hubbard model is presented and carried out to order (t/U) for the one-particle Green function in arbitrary dimension. The spectral weight A(k, ω) is expressed as a Jacobi continued fraction and compared with new Monte-Carlo data of the one-dimensional, half-filled Hubbard model. Different regimes (insulator, conductor and short-range antiferromagne...