Monte Carlo Calculations of the Density of States for a Two-Dimensional Anisotropic Ising Model with Competing Interactions

Abstract

A two-dimensional anisotropic Ising model with competing interactions on a square lattice is investigated using the Monte Carlo approach, based on the Wang–Landau algorithm. The curves of the density-of-states distribution and the order parameter are obtained. It is shown that the density-of-states distribution jumps sharply when |J1/J| = 0.6, due to strong degeneration of the modulated state. Sharp jumps are also observed on the distributions of the order parameter when |J1/J| > 0.2, testifying to the system’s transition from a homogeneous ordered state to a modulated phase.