2008/12/24 by Hiroshi Ueda, Hiroki Nakano, Ueda, Hiroshi +5
Physics and Astronomy · #FOS: Physical sciences #Quantum Physics (quant-ph) #Quantum chaos and dynamical systems #Quantum many-body systems #Statistical Mechanics (cond-mat.stat-mech) #Theoretical and Computational Physics #cond-mat.stat-mech #quant-ph
paper · pdf · doi:10.48550/arxiv.0812.4513
11 pages, 13 figures, submitted to JPSJ
openalex publication_date 2008/12/24 · arxiv created 2009/05/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a way of numerical gap estimation applicable for one-dimensional infinite uniform quantum systems. Using the density matrix renormalization group method for a non-uniform Hamiltonian, which has deformed interaction strength of j-th bond proportional to \cosh λj, the uniform Hamiltonian is analyzed as a limit of λ→ 0. As a consequence of the deformation, an excited quasi-particle is weakly bounded around the center of the system, and kept away from the system boundary. Therefore, insensitivity of an estimated excitation gap of the deformed system to the boundary allows us to have the bulk excitation gap Δ(λ), and shift in Δ(λ) from Δ(0) is nearly linear in λ when λ≪ 1. Efficiency of this estimation is demonstrated through application to the S=1 antiferromagnetic Heisenberg chain. Combining the above estimation and another one obtained from the technique of convergence acceleration for finite-size gaps estimated by numerical diagonalizations, we conclude that the Haldane gap is in [0.41047905,~0.41047931].