ISING_3D_SIMULATION
Monte Carlo 3D Ising Model

ISING_3D_SIMULATION is a FORTRAN90 program which carries out a Monte Carlo simulation of a 3D Ising model.

The text of this Ising model appeared as an example in the ANSI FORTRAN90 standard in 1992. It is a nice presentation of how to use certain features of FORTRAN90, and also demonstrates why one would like to use these features - they make the Ising calculation very simple to describe.

Usage:

ising_3d_simulation n iterations

• n is the number of cells in each dimension. The total number of cells will be n³.
• iterations is the number of iterations to take.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

ISING_3D_SIMULATION is available in a FORTRAN90 version.

Related Data and Programs:

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DUEL_SIMULATION, a FORTRAN90 program which simulates N repetitions of a duel between two players, each of whom has a known firing accuracy.

F90_INTRINSICS, FORTRAN90 programs which illustrate the use of FORTRAN90 intrinsic functions.

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POISSON_SIMULATION, a FORTRAN90 library which simulates a Poisson process in which events randomly occur with an average waiting time of Lambda.

REACTOR_SIMULATION, a FORTRAN90 program which is a simple Monte Carlo simulation of the shielding effect of a slab of a certain thickness in front of a neutron source. This program was provided as an example with the book "Numerical Methods and Software."

THREE_BODY_SIMULATION, a FORTRAN90 program which simulates the behavior of three planets, constrained to lie in a plane, and moving under the influence of gravity, by Walter Gander and Jiri Hrebicek.

TWO_BODY_SIMULATION, a FORTRAN90 program which simulates the behavior of two bodies, constrained to lie in a plane, moving under the influence of gravity, with one body much more massive than the other, creating graphics files for processing by gnuplot.

XISING, a C program which simulates the variation in ferromagnetism in a material, displaying the results using X Windows.

Reference:

1. American National Standard for Programming Language: Fortran - Extended,
   American National Standards Institute, 1992,
   pages 296-299.

Source Code:

• ising_3d_simulation.f90, the source code.

Examples and Tests:

SMALL is a run of a small (N=10) model for a short (ITERATIONS = 25) number of iterations.

• small.txt, the output file.

List of Routines:

• MAIN is the main program for ISING_3D_SIMULATION.
• ISING_3D_INITIALIZE initializes the Ising array.
• TRANSITION carries out a Monte Carlo simulation of a 3D Ising model.
• S_TO_I4 reads an integer value from a string.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the FORTRAN90 source codes.