The Atomic Simulation Environment (ASE) is a set of tools and Python modules for setting up, manipulating, running, visualizing and analyzing atomistic simulations. The code is freely available under the GNU LGPL license.

It requires

• Python 2.7, 3.4-3.6
• NumPy

Optional:

• SciPy
• For ase.gui: Matplotlib (2D Plotting)

It can be installed using PIP

pip install --upgrade --user ase

Full details of the MacOSX installation are here.