Use this URL to cite or link to this record in EThOS:
Title: An approximate study of the Ashkin-Teller and Potts models of statistical mechanics
Author: Ashley, S. E.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1979
Availability of Full Text:
Access from EThOS:
The Ashkin-Teller and q-state Potts models, on the square and triangular lattices, are studied by approximate methods. A series analysis is used to investigate the variation, with q, of the internal energy and specific heat of the Potts model. Estimates of the specific heat exponents are given. A number of real-space renormalization groups are then used to study both models. The decimation and cluster expansion values, for the critical temperature and exponents, imply that larger clusters are needed in order to obtain reliable quantitative results, although even the simplest of these transformations gave an accurate qualitative description of the critical surface of the Ashkin-Teller model. The lower bound variational renormalization group is modified to allow an investigation of the two-layer using representation of the square lattice Ashkin-Teller model. Wherever exact results are available, the transformation proves to be remarkably accurate. A line of fixed points is found, giving exponents which vary continuously with interaction strength. A comparison with the corresponding results for the eight vertex model indicates that, for the same ratio, of four to two-spin couplings, the models have equal exponents.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available