Extension of Structure Integration to Magnetic System

Abstract

We extend our previously developed method, “structure integration”, to evaluate free energy directly for magnetic large systems on a given lattice. The present method expresses the density of states (DOS) as parameters independent of the system but dependent on the lattice, and replaces the DOS unknown a priori as that known a priori. Through the two-dimensional square lattice Ising model, we find that the present method can evaluate magnetic free energy efficiently and accurately above the critical temperature without iterative methods like the Monte Carlo simulation.