Ba2NiIrO6 Tutorial

This chapter shows a complete, practical workflow for running Material-MC with the provided Ba2NiIrO6 example.

Prerequisites

Before running this example, make sure:

  • Material-MC has been built (the executable is build/MMC).

  • MPI is available on your system.

  • You are in the project root directory.

Example files

The example folder contains two required input files:

  • example/Ba2NiIrO6/POSCAR: crystal structure (lattice vectors + atomic positions)

  • example/Ba2NiIrO6/input.toml: Monte Carlo and Hamiltonian settings

In this example:

  • Method: ptmc (parallel tempering Monte Carlo)

  • Temperature range: 0.0 to 400.0

  • Temperature points: 200

  • Supercell size: [8, 8, 4]

  • Magnetic elements: Ni and Ir

  • Model: Heisenberg

Run the simulation

From the project root, run:

mpirun -np 8 ./build/MMC \
  -c example/Ba2NiIrO6/POSCAR \
  -i example/Ba2NiIrO6/input.toml \
  -o Ba2NiIrO6_output.txt \
  -s Ba2NiIrO6_spin

Command-line options:

  • -c: structure file path (POSCAR)

  • -i: parameter file path (TOML)

  • -o: output table file name

  • -s: spin-output filename prefix

Check outputs

After a successful run, check:

  • log.txt: parsed settings and simulation log

  • Ba2NiIrO6_output.txt: thermodynamic results vs. temperature

  • Ba2NiIrO6_spin*: spin structure output files (with your chosen prefix)

What to tune next

A typical next step is editing example/Ba2NiIrO6/input.toml:

  • relaxing_steps / counting_steps for convergence and statistics

  • temperature_points_number for temperature resolution

  • cell_number for system size effects

  • exchange parameters in [[Elements.Neighbors]] for model studies

This gives you a reproducible baseline workflow: keep POSCAR fixed, tune input.toml, and compare output curves from *_output.txt.