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A Non-Crossing Approximation for the Study of Intersite Correlations

Th. Maier·M. Jarrell·Th. Pruschke·J. Keller
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Abstract

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 $N_c$. It is a fully causal and systematic approximation to the full lattice problem, with corrections ${\cal{O}}(1/N_c)$ in two dimensions. The NCA we develop is a systematic approximation with corrections ${\cal{O}}(1/N_c^3)$. 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.

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Th. Maier, M. Jarrell, Th. Pruschke, J. Keller. 1999-06-16. A Non-Crossing Approximation for the Study of Intersite Correlations. https://doi.org/10.1007/s100510050077

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