https://doi.org/10.1007/s100510050077
A non-crossing approximation for the study of intersite correlations
1
Department of Physics, University of Cincinnati, Cincinnati, OH 45221, USA
2
Institut für Theoretische Physik I, Universität Regensburg, 93040 Regensburg, Germany
Received:
16
June
1999
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
