ParticlesMC is a Julia package for performing atomic and molecular Monte Carlo simulations. It is designed to be efficient and user-friendly, making it suitable for both research and educational purposes. Built on top of the Arianna module, it leverages Arianna’s Monte Carlo framework.

MC simulation of a 2D liquid. This example can be reproduced by running particlesmc params.toml in the examples/movie/ folder. Movie generated with ovito.

Features

• Flexible execution: Simulations can be run from standalone scripts or through a command-line interface (CLI), enabling easy integration into workflows.
• Interaction potentials: Supports a broad range of interatomic and intermolecular interaction potentials.
• Monte Carlo moves: Implements state-of-the-art Monte Carlo moves for both atomic and molecular simulations.
• Computational efficiency: Designed with performance in mind to enable fast simulations.
• Arianna framework integration: Leverages the Arianna Monte Carlo framework, benefiting from advanced techniques such as Policy-Guided Monte Carlo (PGMC) and parallel tempering (soon).

Installation

Requirements

• Julia version 1.9 or higher

Installing ParticlesMC

You can install ParticlesMC using the Julia package manager in one of two ways:

1. Using the package mode (press ] in the Julia REPL): julia add https://github.com/TheDisorderedOrganization/ParticlesMC.git

2. Using the Pkg API: julia using Pkg Pkg.add(url="https://github.com/TheDisorderedOrganization/ParticlesMC.git")

Building ParticlesMC

The build should be automatic when installing ParticlesMC. If it hasn't, you can manually build the package, by entering the package mode (press ] in the Julia REPL) and by typing:

julia build This will build the particlesmc executable at ~/.julia/bin (please add this path to your PATH).

Usage

Running a Monte Carlo Simulation

To run a Monte Carlo simulation, you need an input atomic or molecular configuration file (typically with a .xyz extension) and a parameter file (in TOML format). The parameter file specifies both the system details (such as temperature, density, and interaction model) and the simulation details (such as simulation type, number of steps, Monte Carlo moves, and outputs). A minimal example is presented below. More detailed explanations can be found in the documentation.

config.xyz 3 Lattice="1.7321 0.0 0.0 0.0 1.7321 0.0 0.0 0.0 0.0" Properties=type:I:1:pos:R:2 1 0.1585 0.4965 1 1.7215 0.7468 1 0.7606 1.1439

params.toml ```toml [system] config = "config.xyz" temperature = 1.0 density = 1.0 list_type = "LinkedList"

[model] [model."1-1"] name = "LennardJones" epsilon = 1.0 sigma = 1.0 rcut = 2.5

[simulation] type = "Metropolis" steps = 500
seed = 10 parallel = false output_path = "./"

[[simulation.move]] action = "Displacement" probability = 1.0 policy = "SimpleGaussian" parameters = {sigma = 0.05}

[[simulation.output]] algorithm = "StoreTrajectories" schedulerparams = {linearinterval = 50} fmt = "XYZ" ```

Explanation of the example:

This example defines a minimal Monte Carlo simulation setup:

• The [system] section specifies the input configuration file (config.xyz), the simulation temperature and density, and the use of a linked list for neighbor searching.
• The [model] section defines the interaction potential between particles. Here, a Lennard-Jones potential is used for species pair "1-1" with specified parameters (epsilon, sigma, and cutoff rcut).
• The [simulation] section sets the simulation type to Metropolis, the number of Monte Carlo steps to 500, the random seed, whether to run in parallel, and the output path.
• The [[simulation.move]] section describes the Monte Carlo move to use: a displacement move with probability 1.0, guided by a simple Gaussian policy with a standard deviation (sigma) of 0.05.
• The [[simulation.output]] section configures the output: trajectories will be stored every 50 steps in the XYZ format.

By executing particlesmc params.toml you will run a basic Metropolis Monte Carlo simulation of particles interacting via the Lennard-Jones potential, using displacement moves, and periodically saving the system's trajectory.

Contributing

We welcome contributions from the community. If you have a new system or feature to add, please fork the repository, make your changes, and submit a pull request.

Citing

If you use Arianna in your research, please cite it! You can find the citation information in the CITATION file or directly through GitHub's "Cite this repository" button.

License

This project is licensed under the GNU General Public License v3.0. License. See the LICENSE file for details.

Contact

For any questions or issues, please open an issue on the GitHub repository or contact the maintainers.