PANDA

Predicting ANgle from nanoscale Density Analysis — a Python library that determines the contact angle and the interface shape of liquids confined in pores from one-dimensional density profiles of molecular simulations.

Status: pre-alpha. Version 0.0.1 only reserves the package name and fixes the project layout. The library is being rewritten for release; the API described in docs/ is not implemented yet.

Method

Two immiscible liquids in a pore form one of a few interface shapes (droplet, doughnut, worm, roll, perforation, layer). For each shape the density profile across the pore is known analytically as a function of the contact angle θ, the wetting-layer thickness δ and the volume fraction φ. PANDA fits this analytical profile to the profile measured in a simulation, so the position of the interface never has to be located explicitly.

References:

• A. Semenchuk, N. Kondratyuk, I. Kopanichuk, PANDA: Predicting angle from nanoscale density analysis, Colloids Surf. A 708 (2025) 135994. https://doi.org/10.1016/j.colsurfa.2024.135994
• A. Semenchuk, N. Kondratyuk, K. Gerke, I. Kopanichuk, Towards reproducible wetting studies: Automated contact angle determination by molecular simulations, Colloids Surf. A 725 (2025) 137586. https://doi.org/10.1016/j.colsurfa.2025.137586

Installation

pip install panda-md

import panda_md
print(panda_md.__version__)

Development

The project is managed with uv.

make install     # create .venv with the package and the dev tools
make check       # black + ruff + mypy + pytest (the same checks CI runs)
make test-env    # run tests in a separate clean environment (package + test group only)
make build       # build sdist and wheel into dist/
make wheel-check # install the built wheel into an isolated environment and import it
make help        # all commands

Dependency groups in pyproject.toml: test (pytest), lint (black, ruff, mypy), dev (both, installed by default). They are not part of the published package.

Repository layout

src/panda_md/   the package (typed, ships py.typed)
tests/          pytest tests
docs/           design documents: audit of the previous version, architecture specification
smoke/          exploratory scripts run against the previous PANDA version
ROADMAP.md      project plan

Previous version

The original research code lives at https://github.com/FlufffyMelon/PANDA.

License

MIT, see LICENSE.