ESpinS: A program for classical Monte-Carlo simulations of spin systems

TL;DR

ESpinS is a versatile Fortran 90 package for classical Monte Carlo simulations of various spin systems, enabling the analysis of thermodynamic properties including complex interactions and frustrated systems.

Contribution

It introduces a comprehensive, open-source simulation tool capable of modeling diverse spin Hamiltonians with advanced algorithms and user-defined parameters.

Findings

Successfully computes thermodynamic quantities like specific heat and susceptibility.

Supports frustrated and spin glass systems with parallel tempering.

Provides detailed analysis through structure factor and Binder cumulants.

Abstract

We present \texttt{ESpinS} (Esfahan Spin Simulation) package to evaluate the thermodynamic properties of spin systems described by a spin model Hamiltonian. In addition to the Heisenberg exchange term, the spin Hamiltonian can contain interactions such as bi-quadratic, Dzyaloshinskii-Moriya, and single-ion anisotropy. By applying the classical Monte-Carlo simulation, \texttt{ESpinS} simulates the behavior of spin systems versus temperature. \texttt{ESpinS} ables to calculate the specific heat, susceptibility, staggered magnetization, energy histogram, fourth-order Binder cumulants, and the neutron scattering structure factor. Further, it can compute the user-defined magnetic order parameter i.e. summation of projection of spins on the user-defined directions and the physical quantities based on it. \texttt{ESpinS} works by either local update algorithm or parallel tempering algorithm. The latter feature is an appropriate option for considering the frustrated and spin glass magnetic systems. \texttt{ESpinS} is written in Fortran 90 and can be run in single or parallel mode. The package is freely available under the GPL license (see https://github.com/nafiserb/ESpinS ).