1999/01/19 by J. Rosenfeld, J. L. J. Rosenfeld, N. E. Ligterink +2 · 12 citations
Mathematics · Physics and Astronomy · #Condensed matter physics #Coupled cluster #Ferromagnetism #Hamiltonian (control theory) #Heisenberg model #Ising model #Lattice (music) #Mathematics #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum many-body systems #Quantum mechanics #Quantum phase transition #Square lattice #Theoretical and Computational Physics #Wave function #cond-mat
paper · pdf · doi:10.1103/physrevb.60.4030
published in Physical review. B, Condensed matter 60(6), 4030-4042 (American Physical Society) · 22 pages, 3 tables, and 15 figures
arxiv created 1999/01/19 · openalex publication_date 1999/08/01 · arxiv updated 2016/08/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The spin-half XXZ model on the linear chain and the square lattice are examined with the extended coupled-cluster method (ECCM) of quantum many-body theory. We are able to describe both the Ising-Heisenberg phase and the XY-Heisenberg phase, starting from known wave functions in the Ising limit and at the phase transition point between the XY-Heisenberg and ferromagnetic phases, respectively, and by systematically incorporating correlations on top of them. The ECCM yields good numerical results via a diagrammatic approach, which makes the numerical implementation of higher-order truncation schemes feasible. In particular, the best nonextrapolated coupled-cluster result for the sublattice magnetization is obtained, which indicates the employment of an improved wave function. Furthermore, the ECCM finds the expected qualitatively different behaviors of the linear-chain and square-lattice cases.