A NonCrossing Approximation for the Study of Intersite Correlations.pdfVIP

EPJ manuscript No. (will be inserted by the editor) 9 9 9 A Non-Crossing Approximation for the Study of Intersite 1 Correlations n u 1,2 1 2 2 J Th. Maier , M. Jarrell , Th. Pruschke , and J. Keller 6 1 Department of Physics, University of Cincinnati, Cincinnati, OH 45221 1 2 Institut f¨ur Theoretische Physik I, Universit¨at Regensburg, 93040 Regensburg, Germany ] l Received: date / Revised version: date e - r Abstract. We develop a Non-Crossing Approximation (NCA) for the effective cluster problem of the re- t s cently developed Dynamical Cluster Approximation (DCA). The DCA technique includes short-ranged . t correlations by mapping the lattice problem onto a self-consistently embedded periodic cluster of size N . c a It is a fully causal and systematic approximation to the full lattice problem, with corrections O(1/N ) in two c dimensions. The NCA we develop is a systematic approximation with corrections O(1/N 3). The method m c - will be discussed in detail and results for the one-particle properties of the Hubbard model are shown. Near d half filling, the spectra display pronounced features including a pseudogap and non-Fermi-liquid behavior n o due to short-ranged antiferromagnetic correlations. c [ PACS. 7 1.10.Fd – 7 1.27.+a – 7 5.20.Hr – 7 5.30.Kz – 7