Applications of the transfer integral techniques to two-dimensional lattices

R.A. GUYER; P. SERRA; C.A. CONDAT; C.E. BUDDE

PHYSICA A - STATISTICAL AND THEORETICAL PHYSICS

Elsevier Science Publishing

Año: 1986 vol. 136 p. 370 - 392

0378-4371

The transfer integral formalism is used to study the statistical mechanical properties of a two-component field defined on a two-dimensional lattice. This field, taken to have anisotropic elasticity, is subject to both a nonlinear local potential and an external field. The free energy and magnetization are calculated using an approximate solution of the transfer integral problem. This solution employs a strong-coupling approximation to the transfer integral equation and a variational principle with correlated Gaussian trial functions. As a special case, the f4 model for a structural phase transition in the absence of an applied field is analyzed; a phase diagram consistent with previous calculations is obtained. The phase diagram for a two-component field, with anisotropic elasticity, a f4 local potential, and an external field, is also considered.