Thermodynamics of the attractive Hubbard model in dynamic Mean-Field Theory

M. Keller, Walter Metzner, Ulrich Schollwöck

Dario Hügel, Lode Pollet

Giang H. Bach

Giang H. Bach, Jorge G. Hirsch, F. Marsiglio

Erik G. C. P. van Loon, Mikhail I. Katsnelson

We discuss the phase diagram of the extended Hubbard model with both attractive and repulsive local and nonlocal interactions. The extended dynamical mean-field theory (EDMFT) and the dual boson method (DB) are compared. The latter contains additional nonlocal correlation effects that are not incorporated in EDMFT. We find that EDMFT and DB give almost identical results in the attractive V regime, where phase separation occurs. This is quite a difference with the previously studied repulsive V regime, where EDMFT and DB give very different phase boundaries for the checkerboard order phase, especially at small U .

M. Keller, Walter Metzner, Ulrich Schollwöck

We solve the attractive Hubbard model for arbitrary interaction strengths within dynamical mean-field theory. We compute the transition temperature for superconductivity and analyze electron pairing in the normal phase. The normal state is a Fermi liquid at weak coupling and a non-Fermi-liquid state with a spin gap at strong coupling. Away from half filling, the quasiparticle weight vanishes discontinuously at the transition between the two normal states.