lammps-tablegen 0.2.3

Generator for LAMMPS two-body and three-body tabulated potentials.

Tablegen

LAMMPS potential table generator for LAMMPS, developed by Vasilii Maksimov at the Functional Glasses and Materials Modeling Laboratory (FGM²L) at the University of North Texas, under the supervision of Dr. Jincheng Du.

Tablegen is a command-line utility for generating two-body and three-body potential tables for use with LAMMPS simulations. It supports several interaction models commonly used in materials science and glass chemistry, including:

• Teter potential (parametrized by Du and coworkers)
• SHIK potential (Buckingham + Wolf summation)
• Classical Buckingham potential
• Extended Buckingham potential with softening
• Truncated harmonic three-body interactions
• Stillinger-Weber three-body interactions

🔧 Features

• Command-line interface with argparse-based subcommands
• Supports plotting potential curves with matplotlib
• Generates .table and .3b files directly usable in LAMMPS
• Fully modular: new potentials can be added as new handler classes
• Handles numeric precision using mpmath
• Actively developed for materials modeling workflows

📦 Installation

Install from PyPI (preferred)

The package is now published on PyPI you can install the latest stable release with:

pip install lammps-tablegen

Install directly from GitHub (bleeding‑edge)

If you need the most recent commit:

pip install git+https://github.com/superde1fin/tablegen.git

Clone & install locally

For local experimentation or contributing:

git clone https://github.com/superde1fin/tablegen.git
cd tablegen

# Standard install (no dev extras)
pip install .

# OR editable install (auto‑reload while editing)
pip install -e .

Tip : add the [dev] extra to pull in testing, type‑checking, and release tools:

pip install .[dev]

This installs pytest, ruff, mypy, twine, and other developer utilities declared in pyproject.toml.

Requires Python ≥ 3.9 and a working C/Fortran toolchain if installing numpy from source.

🥪 Usage

After installation, invoke the CLI with:

tablegen [style] [options]

Available styles:

• teter: Generate two-body tables using the Teter potential

$$ \begin{gather*} V^{short} = A_{ij} \exp(-\frac{r_{ij}}{\rho_{ij}}) - \frac{C_{ij}}{r_{ij}^6}\ V^{\prime}= \frac{B_{ij}}{r^{n_{ij}}} + D_{ij}r_{ij}^2 \end{gather*} $$

Note: Second potential energy curve is added at the Buckingham inflection point as a shor-range correction. This potential defines cation to oxygen (and O-O) interactions. The rest should be added manually as coulombic interactions with Ewald summation and percision of 1e-6. Charges of each atomic species will be printed out.

• shik: Generate two-body tables using the SHIK potential

$$ \begin{gather*} V^{SHIK} = V^{Buck} \left( r_{\alpha\beta} \right) + V^{Wolf}\left( r_{\alpha\beta} \right)\ V^{Buck} \left( r_{\alpha\beta} \right) = A_{\alpha\beta} \exp\left( -B_{\alpha\beta} r_{\alpha\beta} \right) - \frac{C_{\alpha\beta}}{r_{\alpha\beta}^6} + \frac{D_{\alpha\beta}}{r_{\alpha\beta}^{24}}\ V^W \left( r_{\alpha\beta} \right) = q_{\alpha} q_{\beta} \left( \frac{1}{r_{\alpha\beta}} - \frac{1}{r_{cut}^W} + \frac{r_{\alpha\beta} - r_{cut}^W}{\left( r_{cut}^W \right)^2} \right) \end{gather*} $$

Note: Currently the pairs with published coefficients will have the wolf part added while no potential entry will be generated for a pair without coefficients (i.e. Na-Al)

• buck: Generate tables using the standard Buckingham potential

$$ \begin{gather*} V\left( r_{ij} \right) = A_{ij} \exp\left( -\frac{r}{\rho_{ij}} \right) - \frac{C_{ij}}{r^6} \end{gather*} $$

• buck_ext: Use the extended Buckingham potential with softened short-range repulsion

$$ \begin{gather*} V\left( r_{ij} \right) = A_{ij} \exp\left( -\frac{r}{\rho_{ij}} \right) - \frac{C_{ij}}{r^6} \left( 1 - \exp\left( - \left( \frac{r_{ij}}{43\rho_{ij}} \right)^6 \right) \right) + \frac{D_{ij}}{r_{ij}^{12}} \end{gather*} $$

• 3b_trunc: Generate three-body truncated harmonic tables

$$ \begin{gather*} V\left(r_{ij}, r_{ik}, \theta_{jik}\right) = \frac{k}{2} (\theta_{jik} - \theta_0)^2 \exp\left(-\frac{r_{ij}^8 + r_{ik}^8}{\rho^8}\right) \end{gather*} $$

• sw: Generate three-body Stillinger-Weber potential energy tables

$$ \begin{gather*} V\left(r_{ij}, r_{ik}, \theta_{jik}\right) = \lambda_{ijk}\epsilon_{ijk}\left( \cos\theta_{ijk} - \cos\theta_{0ijk} \right)^2 \exp\left( \frac{\gamma_{ij}\sigma_{ij}}{r_{ij} - a_{ij}\sigma_{ij}} \right)\exp\left( \frac{\gamma_{ik}\sigma_{ik}}{r_{ik} - a_{ik}\sigma_{ik}} \right) \end{gather*} $$

Example usage:

PLEASE MAKE SURE TO READ THE HELP INFORMATION THOROUGHLY BEFORE USING EACH STYLE

Minimal Teter potential generation for SiO2:

tablegen teter Si Na

Standard options invoked:

tablegen teter Si Na --cutoff 8 --data_points 10000 --table_name TETER.table --plot -10 10

Minimal SHIK potential generation for SiO2:

tablegen shik initial.structure Si O

Standard options invoked:

tablegen shik initial.structure Si O --cutoff 8 --data_points 10000 --table_name SHIK.table --plot -10 10

or equivalently

tablegen shik initial.structure Si O -c 8 -d 10000 -t SHIK.table -p -10 10

Minimal Buckingham potential table generation (user will be prompted for coefficients):

tablegen buck Na-O Si-O

Standard options invoked

tablegen buck Na-O Si-O -c 10 -d 5000 -t buck.table -p -20 10

Minimal truncated three-body potential table generation (user will be prompted for coefficients):

tablegen 3b_trunc Si-O-Si

Standard options invoked:

tablegen 3b_trunc Si-O-Si -t silica -d 30 -c 5

Minimal Stillinger-Weber potential table generation (user will be prompted for coefficients):

tablegen sw Si-O-Si

Standard options invoked:

tablegen sw Si-O-Si -t silica -d 30 -c 5

💡 LAMMPS input file generation

All styles support minimal LAMMPS input file generation with the -f option:

tablegen shik -f

or to use custom input file name:

tablegen shik -f input.lammps

Some key details required by LAMMPS are written into the input file with their values as well as placeholders (???). For styles TETER and SHIK a suggested glass melt-quench procedure is also appended to the input file.

⚛️ Suppported elements

For some styles (TETER and SHIK) potential generation depends on built-in parameters of their forms. To see what elements are supported and what pairwise interactions are defined use the -s option:

tablegen teter -s

This will show the support message and exit without generating any files.

📚 Documentation

All styles support -h or --help flags for detailed usage:

tablegen shik --help

🧠 Design Overview

The project is modular:

• cli.py: Main entry point, defines CLI and parses arguments
• handlers/: Contains one handler class per potential type (SHIK, BUCK, etc.)
• constants.py: Shared constants (e.g., cutoffs, physical constants, default coefficients)
• utils.py: Supporting classes and functions used by cli and handlers
• __init__.py: Exposes handler classes and version metadata
• pyproject.toml: Build and dependency metadata

Each handler:

• Parses user-provided arguments
• Validates species/pair/triplet input
• Prompts for coefficients if not hardcoded into constants
• Provides `getter methods for cli to perform general operations

📈 Plotting

If the --plot option is passed, matplotlib will be used to visualize the potential curves for the specified pairs or triplets.

🥪 Development

Install dev dependencies:

pip install .[dev]

Run tests:

pytest

🔖 License

GNU General Public License v3.0 (GPLv3). See LICENSE for details.

👤 Author

Vasilii Maksimov
University of North Texas
✉️ [e-mail]

🌐 Links

• 🔬 LAMMPS Official Site
• 📆 PyPI Page
• 🐙 GitHub Repository