Teoria de campo médio com clusters correlacionados aplicada ao modelo de Ising antiferromagnético

Abstract

The correlated cluster mean-field theory is an approximative method that has presented good accuracy and low computational cost results when applied to ferromagnetic systems. However, due to its recent publication, the technique does not have a known application to antiferromagnetic systems yet, despite the great importance of the study of these systems too. Thus, we propose an application proposal of the correlated cluster mean-field theory to the Ising model with antiferromagnetic interactions. This application consists of the separation of mean fields acting over the system, which aims at adapting these fields to the fundamental state. This differentiation allowed the application of the technique, so it was possible to obtain results for the sublattice magnetization, internal energy, specific heat and the magnetic susceptibility, with error less than 6% in comparison with the exact results and good concordance in relation to the expected behavior for the treated magnetic systems. The application of this technique to an antiferromagnetic system is an important step in the verification of the limits of validity of the method and the understanding of its main characteristics.