A non-crossing approximation for the study of intersite correlations
Department of Physics, University of Cincinnati, Cincinnati, OH 45221, USA
2 Institut für Theoretische Physik I, Universität Regensburg, 93040 Regensburg, Germany
Published online: 15 February 2000
We develop a Non-Crossing Approximation (NCA) for the effective cluster problem of the recently developed Dynamical Cluster Approximation (DCA). The DCA technique includes short-ranged correlations by mapping the lattice problem onto a self-consistently embedded periodic cluster of size Nc. It is a fully causal and systematic approximation to the full lattice problem, with corrections in two dimensions. The NCA we develop is a systematic approximation with corrections . The method will be discussed in detail and results for the one-particle properties of the Hubbard model are shown. Near half filling, the spectra display pronounced features including a pseudogap and non-Fermi-liquid behavior due to short-ranged antiferromagnetic correlations.
PACS: 71.10.Fd – Lattice fermion models (Hubbard model, etc.) / 71.27.+a – Strongly correlated electron systems; heavy fermions / 75.20.Hr – Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000