title: Dynamics of the transverse Ising model with next-nearest-neighbor interactions.
abstract: We study the effects of next-nearest-neighbor (NNN) interactions on the dynamics of the one-dimensional spin-1/2 transverse Ising model in the high-temperature limit. We use exact diagonalization to obtain the time-dependent transverse correlation function and the corresponding spectral density for a tagged spin. Our results for chains of 13 spins with periodic boundary conditions produce results which are valid in the infinite-size limit. In general we find that the NNN coupling produces slower dynamics accompanied by an enhancement of the central mode behavior. Even in the case of a strong transverse field, if the NNN coupling is sufficiently large, then there is a crossover from collective mode to central mode behavior. We also obtain several recurrants for the continued fraction representation of the relaxation function.
authors.affiliation: Departamento de Física, Universidade Federal de Viçosa, 36571-000 Viçosa, Minas Gerais, Brazil.
authors.forename: P R C
authors.initials: PR
authors.lastname: Guimarães
authors.affiliation: Universidade Federal da Paraíba, Centro de Ciências Exatas e da Natureza-Campus I, Departamento de Física, CCEN Cidade Universitária-João Pessoa, PB, Brazil and Department of Physics and Astronomy, University of Georgia, 30602 Athens, Georgia, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Plascak
authors.affiliation: Department of Physics, University of Portland, Portland, Oregon 97203, USA.
authors.forename: O F
authors.initials: OF
authors.lastname: de Alcantara Bonfim
authors.affiliation: Departamento de Física, Universidade Federal Fluminense, Av. Litorânea s/n, Niterói, 24210-340, RJ, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Florencio