Physical review. B, Condensed matter
Dynamics of the strong anisotropic three-dimensional Ising model in a transverse field
J. A. Plascak, F. C. Sá Barreto, Antonio S. T. Pires
Abstract
The dynamics of the three-dimensional anisotropic spin-\textonehalf{} Ising model in a transverse field is studied above ${T}_{c}$ by a method in which the coupled-chain problem is reduced to that of a single chain in an effective field. The problem of a single chain is studied by means of Mori's continued-fraction expansion in a four-pole approximation. The moments are obtained by using the time-dependent correlation function calculated in the $c$-cyclic and in the improved $c$-cyclic approximations [J. Phys. A 13, 223 (1980)]. A comparison between these two approximations is done by calculating the critical temperature as function of the tunneling field. The one-dimensional correlation length is obtained, and it agrees well with the experimental results for the quasi-one-dimensional ferroelectric Cs${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$.