A blender addon to import Gaussian cube files and atomic XYZ files. Requires -atomic simulation environment and -scikit-image.
It can be a bit tricky to install these as blender uses its own bundled python. If you install one of these packages and yet blender can't seem to find it, check the answers here to install in the right place.
Once you have those installed, you can use these folders as regular blender addons. They are added from the user preferences as can be seen here.