Welcome to WEAS Widget!

A widget to visualize and edit atomic structures in Jupyter Notebooks. It uses WEAS (Web Environment For Atomistic Structure) in the backend.
Interact with the widget using LLM agents (e.g., LangChain) to guide edits and analysis from your notebook.
Features:
- Model: space-filling, ball-stick, polyhedral.
- Supports importing data from ASE and Pymatgen.
- Edit structure: move, rotate, delete and replace atoms.
- Supports periodic boundary conditions
- Animations
- Isosurfaces
- Vector fields, e.g., magnetic moments, phonons, ...
- Fermi surface
- Lattice planes
- Integrate with LLMs via LangChain Agent
Demo
Please try the widget in the following links:

🌟 Gallery: projects using weas-widget
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Installation
With pip:
pip install weas-widget
To install the latest version from source, first clone the repository and then install using pip:
git clone https://github.com/superstar54/weas-widget
cd weas-widget
npm install
npm run build
pip install -e .
How to use
from ase.build import molecule
from weas_widget import WeasWidget
atoms = molecule("C2H6SO")
viewer = WeasWidget()
viewer.from_ase(atoms)
viewer
Full documentation at: https://weas-widget.readthedocs.io/en/latest/index.html
Reporting issues
If you encounter any problems, please first update the widget to the latest version.
pip install weas-widget --upgrade
If the problem persists, please open a GitHub issue
Features
Select Atoms
- Pick Selection: Click directly on an atom to select it.
- Range Selection: Hold the
Shift key and drag the right mouse button to select a group of atoms.
Move, Rotate selected atoms
Press the keyboard shortcut, and move your mouse.
Delete selected atoms
Press the Delete key
Export
- Export the modified atomic structure to ASE or Pymatgen
atoms = viewer.to_ase()
viewer.save_image("/home/xing/filename.png")
viewer.download_image("filename.png")
Different styles for the atoms.
Visualizing crystal structures
For a nice visualization of a crystal, show
- unit cell
- bonded atoms outside the cell
- polyhedra
from weas_widget import WeasWidget
viewer1 = WeasWidget()
viewer1.load_example("tio2.cif")
viewer1.avr.model_style = 2
viewer1.avr.boundary = [[-0.1, 1.1], [-0.1, 1.1], [-0.1, 1.1]]
viewer1.avr.show_bonded_atoms = True
viewer1.avr.color_type = "VESTA"
viewer1
Isosurfaces
from ase.build import molecule
from weas_widget import WeasWidget
from ase.io.cube import read_cube_data
volume, atoms = read_cube_data("h2o-homo.cube")
viewer = WeasWidget()
viewer.from_ase(atoms)
viewer.avr.iso.volumetric_data = {"values": volume}
viewer.avr.iso.settings = {"positive": {"isovalue": 0.001},
"negative": {"isovalue": -0.001, "color": "yellow"}
}
viewer
Fermi surface
from weas_widget import WeasWidget
viewer = WeasWidget()
viewer.add_fermi_surface_from_bxsf("copper.bxsf", clip_bz=True)
viewer
Magnetic moments
Show the magnetic moments as a vector field.
from ase.build import bulk
from weas_widget import WeasWidget
import numpy as np
atoms = bulk("Fe", cubic=True)
atoms*=[2, 2, 1]
atoms.set_array("moment", np.ones(len(atoms)))
viewer = WeasWidget()
viewer.from_ase(atoms)
viewer.avr.model_style = 1
viewer
Phonons
Animate vibrational (phonon) modes (computed with external software).
import numpy as np
from ase.build import bulk
from weas_widget import WeasWidget
atoms = bulk("Fe", cubic=True)
phonon_setting = {"eigenvectors": np.array([[[0, 0], [0, 0],[0.5, 0]],
[[0, 0], [0, 0], [-0.5, 0]]]
),
"kpoint": [0, 0, 0],
"amplitude": 5,
"factor": 1.5,
"nframes": 20,
"repeat": [4, 4, 1],
"color": "blue",
"radius": 0.1,
}
viewer = WeasWidget()
viewer.from_ase(atoms)
viewer.avr.phonon_setting = phonon_setting
viewer
Lattice plane
Draw a plane that is defined by the miller indices and distance from the origin or by selecting the atoms.
viewer.avr.lp.add_plane_from_indices(name = "111",
indices = [1, 1, 1],
distance = 4,
scale = 1.0,
color = [0, 1, 1, 0.5])
viewer.avr.lp.build_plane()
Slice 2D
from ase.build import molecule
from weas_widget import WeasWidget
from ase.io.cube import read_cube_data
volume, atoms = read_cube_data("h2o-homo.cube")
viewer = WeasWidget()
viewer.from_ase(atoms)
viewer.avr.model_style = 1
viewer.avr.volume_slice.volumetric_data = {"values": volume}
viewer.avr.volume_slice.settings = {"Slice 1": {"h": 0, "k": 1, "l": 0, "distance": 5.5, "samplingDistance": 0.1 },
"Slice 2": {"h": 1, "k": 1, "l": 0, "distance": 5.5, "samplingDistance": 0.1 },
}
viewer.camera.setting = {"direction": [0.5, 1, 2], "zoom": 1.5}
viewer
Save and restore state
state = viewer.export_state()
viewer.save_state("snapshot.json")
viewer.load_state("snapshot.json")
viewer = WeasWidget.from_state_file("snapshot.json")
Integrate with LangChain Agent
WeasToolkit provides agent-ready tools for inspection and editing (style controls, selection, structure loading, atom edits, camera, measurements, meshes, and more). You can also extend it with your own tools.
from weas_widget import WeasWidget, WeasToolkit
from langchain_openai import ChatOpenAI
from langchain_widget import LangChainWidget
from langchain_openai import ChatOpenAI
from dotenv import load_dotenv
import ipywidgets as ipw
load_dotenv()
viewer = WeasWidget()
chat_model = ChatOpenAI(model="gpt-4o-mini")
chat = LangChainWidget(
chat_model=chat_model,
tools=WeasToolkit(viewer=viewer),
title="WEAS Agent Chat",
system_prompt=(
"You are a scientific assistant. "
"Use the available tools to inspect and manipulate the 3D structure."
),
)
ipw.VBox([viewer, chat])
See the agent tools reference in the docs: https://weas-widget.readthedocs.io/en/latest/agent_tools.html
Test
Unit test
pytest
End-to-end test
The e2e test is similar to ipywidgets.
For the first time, one needs to install the dependence.
cd tests/notebooks/
yarn install
Then run in a terminal:
yarn start
In another terminal:
yarn test
If the snapshots need to be updated:
yarn test:update
Contact
License
MIT