Atomic Simulation Environment (ASE)

3.28.0 · active · verified Sun Apr 12

The Atomic Simulation Environment (ASE) is a comprehensive Python library designed for setting up, manipulating, running, visualizing, and analyzing atomistic simulations. It offers a flexible framework that integrates with various external simulation codes through its Calculator interface, supporting methods ranging from Density Functional Theory (DFT) to semi-empirical and classical interatomic potentials. ASE is actively maintained with frequent feature and bugfix releases; the current stable version is 3.28.0.

Warnings

breaking ASE now requires Python 3.10 or newer, starting with version 3.27.0. Ensure your Python environment meets this requirement.
Fix: Upgrade Python to 3.10+ or use an older ASE version if Python 3.9- is required.
breaking The `ase.ga` (genetic algorithm) module has moved to a standalone project, `ase-ga`, in version 3.27.0. It is no longer part of the main `ase` package.
Fix: Install `ase-ga` separately via `pip install ase-ga` if you use genetic algorithms.
breaking The Optimizable interface (used by Optimizers) changed in version 3.26.0 to work with arbitrary degrees of freedom instead of Cartesian (Nx3) ones. This can break code that uses internal Optimizer features like `converged()`.
Fix: Review custom optimizer implementations or code interacting with optimizer internals. Adapt to the new arbitrary degrees of freedom interface.
breaking The `ase.io.orca.read_orca_output` function now returns an `Atoms` object with attached properties, instead of just a results dictionary. The previous behavior is available via `ase.io.orca.read_orca_outputs()`.
Fix: Adjust code that reads ORCA output to expect an `Atoms` object, or explicitly call `read_orca_outputs()` for the dictionary-only return.
deprecated The `master` parameter to Optimizers is now keyword-only. The `force_consistent` option has been removed from `Optimizer`.
Fix: Pass `master` as a keyword argument (e.g., `BFGS(atoms, master=...)`) and remove any usage of `force_consistent` from optimizer initialization.

Install

pip install ase Install stable release from PyPI

Imports

Atoms
```
from ase import Atoms
```
EMT
```
from ase.calculators.emt import EMT
```
Example of importing a built-in calculator.
BFGS
```
from ase.optimize import BFGS
```
Example of importing an optimizer.

Quickstart

This example demonstrates how to create an `Atoms` object, attach a simple `EMT` calculator, perform a geometry optimization using `BFGS`, and save the final structure and energy. ASE defaults to eV and Å for units.

from ase import Atoms
from ase.calculators.emt import EMT
from ase.optimize import BFGS
from ase.io import write

# Create a molecule (H2)
h2 = Atoms('H2', positions=[[0, 0, 0], [0, 0, 0.7]])

# Attach a calculator (Empirical Potential)
h2.calc = EMT()

# Optimize the geometry
optimizer = BFGS(h2, trajectory='h2.traj')
optimizer.run(fmax=0.02)

# Print final energy and write structure
print(f'Final potential energy: {h2.get_potential_energy():.3f} eV')
write('H2.xyz', h2)

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