Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Series

1984

University of Portland

Articles 1 - 3 of 3

Full-Text Articles in Physics

Critical Behavior Of The One-Dimensional S = 1 Xy Model With Single-Ion Anisotropy, O. F. De Alcantara Bonfim, T. Schneider Aug 1984

Critical Behavior Of The One-Dimensional S = 1 Xy Model With Single-Ion Anisotropy, O. F. De Alcantara Bonfim, T. Schneider

Physics Faculty Publications and Presentations

We study the quantum critical behavior of the one-dimensional, S = 1 XY model in the presence of a single-ion anisotropy. Using a path-integral approach, we obtain, at T = 0 and for a positive anisotropy constant, a classical free-energy functional that allows discussion of the critical properties. The rescaling of frequencies is governed by the critical exponent z = 1. Renormalization-group arguments reveal that at criticality the system belongs to the same universality class as the isotropic 2-d XY model.


Computer Simulations Of Submicron Fib System Optics, W. Thompson, I. Honjo, Mark Utlaut Jan 1984

Computer Simulations Of Submicron Fib System Optics, W. Thompson, I. Honjo, Mark Utlaut

Physics Faculty Publications and Presentations

The design of the optical elements for a focused ion beam (FIB) system having a 50 mm spot size over a 1 mm square field requires extensive computational analysis. We discuss the mathematical techniques applied to the components of interest in this submicron FIB system; the electrostatic lenses, the mass analyzer, and the electrostatic deflectors. The results of ion trajectory calculations predicted for the whole FIB column by the computer code snow are presented. The aberration coefficients to third order and a parametric study of a stigmatic Wien filter whose design includes entrance and exit fringe field effects will be ...


Non-Perturbative Renormalisation Using Dimensional Regularisation: Applications To The Ε Expansion, A. J. Mckane, D. J. Wallace, O. F. De Alcantara Bonfim Jan 1984

Non-Perturbative Renormalisation Using Dimensional Regularisation: Applications To The Ε Expansion, A. J. Mckane, D. J. Wallace, O. F. De Alcantara Bonfim

Physics Faculty Publications and Presentations

We give a prescription for the one-loop renormalisation of the imaginary parts of vertex functions in gø4, which are generated when gR < 0 is non-perturbative in ɛ. This fixed point determines the imaginary parts of the critical exponents which are generated when ɛ < 0, and allows us to determine the high-order behaviour of the perturbation series in E for these exponents. The generalisation of these ideas to the O(n) symmetric g(ø2)2 model is also given.