title: Parquet approximation for the 4x4 Hubbard cluster.
abstract: We present a numerical solution of the parquet approximation, a conserving diagrammatic approach which is self-consistent at both the single-particle and the two-particle levels. The fully irreducible vertex is approximated by the bare interaction thus producing the simplest approximation that one can perform with the set of equations involved in the formalism. The method is applied to the Hubbard model on a half-filled 4x4 cluster. Results are compared to those obtained from determinant quantum Monte Carlo (DQMC), FLuctuation EXchange (FLEX), and self-consistent second-order approximation methods. This comparison shows a satisfactory agreement with DQMC and a significant improvement over the FLEX or the self-consistent second-order approximation.
authors.affiliation: Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: S X
authors.initials: SX
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Fotso
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: T A
authors.initials: TA
authors.lastname: Maier
authors.forename: K
authors.initials: K
authors.lastname: Tomko
authors.forename: E F
authors.initials: EF
authors.lastname: D'Azevedo
authors.forename: R T
authors.initials: RT
authors.lastname: Scalettar
authors.forename: T
authors.initials: T
authors.lastname: Pruschke
authors.forename: M
authors.initials: M
authors.lastname: Jarrell
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons; D008962:Models, Theoretical; D011789:Quantum Theory