Year: 2009
Type: dissertation
Abstract: In this dissertation, we use the recently developed Entanglement Perturbation Theory (EPT) to solve antiferromagnetic spin chain problems, for both spin 1/2 and spin 1. We firs use EPT-g (EPT algorithm for ground state) to get the ground state properties. We calculated precisely energies, magnetization and spin-spin correlations. The precision of the long range spin-spin correlation functions for spin 1/2 chains is unprecedented. Due to its special structure, we also use EPT-g to calculate the firs excited state properties for spin 1 chains. Hence we plotted the phase diagram for spin 1 xxz chains. Also a generalization of EPT (EPT-e) for elementary excitation in one dimension determined the spin-triplet magnon spectrum for spin 1 chain for the firs time for the entire Brillouin zone, including the Haldane gap at k = π. The spin chains, the 2D&3D Ising models, the 1D&2D Hubbard models and the Bose-Hubbard model whose study by EPT is recently started represent a variety of strongly correlated many body systems with translational symmetry. Namely EPT is a general method for them. On the other hand, the successful application of EPT-e indicates EPT's potential to study the inhomogeneous quantum systems.
Author: Lihua Wang
Institution: Western Michigan University
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Ball State University
OpenAlex ID: W1933596166