A cluster density matrix for the effective field theory with correlations

TL;DR

This paper introduces a cluster density matrix approach for the Ising model with spin 1/2, enabling self-consistent calculations of thermodynamic averages within an effective field theory framework.

Contribution

It develops a new cluster density matrix method for the Ising model, facilitating improved self-consistent thermodynamic calculations in effective field theories.

Findings

Derivation of Gibbs free energy using the new cluster density matrix.

Enhanced self-consistent calculation of thermodynamic averages.

Application to the Ising model with spin 1/2.

Abstract

A cluster density matrix is introduced in the form suitable for the self-consistent calculation of relevant thermodynamic averages for the Ising model with spin S=1/2. On this basis, derivation of the Gibbs free-energy for the effective field theory of Honmura and Kaneyoshi is presented.